

Technical Paper 248 


DEPARTMENT OF THE INTERIOR 

ALBERT B. FALL, Secretary 


U BUREAU OF MINES 

H. FOSTER BAIN, Director 


GAS MASKS FOR GASES MET IN 
FIGHTING FIRES 


BY 

ARNO C. FIELDNER, SIDNEY H. KATZ 
and SELWYNE P. KINNEY 




5 


WASHINGTON 

GOVERNMENT PRINTING OFFICE 


The Bureau of Mines, in carrying out one of the provisions of its organic act—to 
disseminate information concerning investigations made—prints a limited free 
edition of each of its publications. 

When this edition is exhausted, copies may be obtained at cost price only through 
the Superintendent of Documents, Government Printing Office, Washington, D. C. 

The Superintendent of Documents is not an official of the Bureau of Mines. His is 
an entirely separate office and he should be addressed: 

Superintendent op Documents, 

Government Printing Office, 

Washington, D. C. 

The general law under which publications are distributed prohibits the giving 
of more than one copy of a publication to one person. The price of this publication 
is 25 .cents. 

Persons desiring for lecture. purposes the use, free of charge, of lantern slides of 
the illustrations in this publication should make request of the Director of the Bureau 
of Mines, Washington, D. C. 

First edition . August, 1921. 


LIBRARY OF CONGRESS 

received 

APR 131922 

documents, division 









A 


r* 



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CONTENTS. 


Introduction... 

Acknowledgments.. 

Experiences of fire fighters where masks were inadequate. 

Experiences where masks were useful. 

Discussion of the experiences. 

The chemistry of combustion. 

Products of complete combustion. 

Products of incomplete combustion... 

Properties and effect on man of various products of combustion. 

Carbon dioxide. 

Carbon monoxide.. 

Symptoms of carbon monoxide poisoning. 

Detection of carbon monoxide—.... 

Soot, tar, and smoke vapors.. 

Other poisonous and asphyxiating gases encountered by firemen. 

Oxides of nitrogen. 

Sulphur dioxide. 

Ammonia......... 

Treatment for ammonia poisoning. 

Chlorine. 

Illuminating gas. 

Gasoline and petroleum vapors. 

Acid and miscellaneous chemical vapors. 5 . 

Gases from carbon tetrachloride fire extinguishers. 

Phosgene.-. 

Hydrochloric acid gas. 

Carbon tetrachloride. 

Types of breathing apparatus. 

Self-contained oxygen breathing apparatus. 

“Pig snout’ ? respirators. 

Air masks and helmets. 

Description and properties of the United States Army type of gas masks.. 

Construction. 

Care and inspection of gas masks. 

How to put on a gas mask. 

Absorbents for gases.. 

Charcoal.-. . . 

Soda-lime. 

Mixed charcoal and soda-lime. 

A mm onia absorbents. 

Silica gel.. 

Absorbent for carbon monoxide. 

Gases and atmosphere^ against which the gas mask does not protect. 

*v 


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CONTENTS. 


Page. 


Experiments with incompletely burning fires. 30 

Experiments with charcoal fires. 30 

Experiments with fires in a closed room. 31 

Results of tests with fires in a closed room. 35 

Discussion of results of tests with fires. 35 

Experiments with carbon tetrachloride fire-extinguisher liquids. 38 

Discussion of results of tests with liquids containing carbon tetrachloride.. 42 

Atmospheres in burning mines. 43 

Utility of Army gas masks in fighting fires. 43 

Recommended gas mask for fire fighters. 45 

Specifications for fire-fighters’ gas mask. 46 

Requirements for Bureau of Mines approval. 46 

Summary and conclusions. 51 

Appendix. 55 

Conversion table for gases—parts per million versus milligrams per liter.. 55 

Poisonous doses of industrial gases and vapors in air. 56 

Publications on mine fires and on oxygen-breathing apparatus. 57 

Index. 59 


TABLES. 


Table 1. Gases and atmospheres in which gas masks are inadequate. 30 

2. Results of tests with smoldering fires in closed room. 36 

3. Results of tests with different masks and respirators in smoke. 37 

4. Results of distillation of carbon tetrachloride fire-extinguisher liquids 39 

5. Results of experiments with heated carbon tetrachloride fire-extin¬ 

guisher liquids in the closed chamber. 41 

6. Analyses of gases from mine fires. 44 

7. Colors to indicate purpose of masks. 46 

8. Conversion table for gases: Parts per million versus milligrams per 

liter. 52 

9. Poisonous doses of industrial gases and vapors in air. 56 




























ILLUSTRATIONS. 


Page. 

Plate I. Gibbs apparatus, developed by the Bureau of Mines. 20 

II. Salvus light apparatus. 21 

III. A, ‘‘Pig snout” respirator containing a moistened sponge; B, “Pig 

snout ” respirator with paper filter for dust and smoke. 22 

IV. A, Man wearing a Tissot mask tightening gas slide joint; B, Man 

equipped with Tissot mask and air hose. 23 

Y. A, R. F. K. mask used by the United States Army; B, Air mask 
supplied with fresh air through long hose; C, Tissot type of United 

States Army gas masks. 24 

YI. Small canister with mouthpiece directly attached, supported by the 

teeth. 25 

VII. A, Adjusting gas mask; B, Adjusting mask with one movement. 26 

VIII. Apparatus for demonstrating the inadequacy of the Army canister 

for protection against carbon monoxide. 30 

IX. Gas chamber at the Pittsburgh experiment station of the Bureau of 

Mines. 31 

Figure 1. Details of the R. F. K. mask. 23 

2. Apparatus used for making smouldering fires. 24 

3. Detail of gas chamber used at the Pittsburgh experiment station of 

the Bureau of Mines for experimental purposes. 32 

4. Army gas-mask canister. 33 

5. Curves showing relation between change of composition of gases in 

the experimental chamber, with time during experimental fires. 34 


v 



















GAS MASKS FOR GASES MET IN FIGHTING FIRES. 


By Arno C. Fieldner, Sidney H. Katz, and Selwyne P. 

Kinney. 


INTRODUCTION. 

The Bureau of Mines has tested and used many types of self- 
contained oxygen breathing apparatus in fighting mine fires and in 
rescuing miners trapped in poisonous gases resulting from fires or from 
explosions in mines. Similar devices have been used by city fire fighters 
but have never been considered entirely satisfactory owing, largely, 
to their weight, to the time necessary for adjusting them to wearers, 
and the constant care required to maintain the apparatus in good 
working condition. Hence there has long been need for a light, 
easily adjusted, and dependable breathing apparatus for protecting 
fire fighters from irritating and poisonous gases and smokes. 

As a result of the war the gas mask, which uses a chemical filter 
for removing poisonous gases and fumes from air, has been developed 
to a high state of perfection. The mask used by the United States 
Army is capable of giving complete protection against all the deadly 
gases that have been met on the battle field, but it does not protect 
against all the gases or atmospheres encountered in mines and in the 
industries and in fire fighting. 

The dangers from gases that city firemen face and the need of 
standardized methods of protection against them have been pointed 
out by Chief John Kenlon, 1 of the fire department of New York City, 
who also mentioned the knowledge firemen should have of' gases. 
The need of such knowledge has been especially emphasized by over- 
confidence in the capacity of the Army type of gas mask to protect 
the wearer against industrial gases, an assurance that has probably 
arisen because soldiers were taught that the United States Army gas 
mask would protect them against all the gases they might encounter. 
This statement, true for the battle field but not true for all industrial 
gases, including products of combustion, has been brought back by 
soldiers and spread generally among workers. Furthermore, city 
firemen and mine operators have been circularized with letters and 
advertisements of Army gas masks offered for sale by certain persons 

i Proceedings of International Association of Fire Engineers, Fire and Water Eng., vol. 66, July 30,1919, 
p. 239. 


3 





4 


GAS MASKS FOR GASES MET IN FIGHTING FIRES. 


who made unreserved statements, probably through ignorance, that 
the masks would protect wearers in mines and burning buildings. 
The falsity of these statements was evident to the Bureau of Mines, 
which took steps immediately to notify the public that Army gas 
masks had serious limitations, especially when used in fire fighting 
or in any place where unusually heavy amounts of poisonous gas are 
present. This warning has been verified by the actual experiences 
of some city firemen who have tried Army masks. On the other 
hand the excellent qualities of the masks have also been demonstrated 
at fires. 

The work described in this paper was undertaken to obtain infor¬ 
mation regarding the use of the Army type of mask for fighting fires 
and for doing rescue work in mines and the mineral industries. 
Incidentally, the results may be of interest to city firemen, insurance 
underwriters, state officials, property owners, and others who are 
interested in protection of property from fire. 

There have also been included herein descriptions of breathing 
apparatus other than gas masks, descriptions of most of the gases 
met in the industries, of their physiological effects when inhaled, and 
of methods of treating persons who have been gassed. 

ACKNOWLEDGMENT S. 

The authors wish to express their grateful appreciation of the 
many suggestions and valuable criticisms received from George S. 
Rice, chief mining engineer of the Bureau of Mines, who suggested an 
investigation of the application of Army gas masks to industrial uses, 
and from E. A. Holbrook, assistant director of the Bureau of Mines, 
whose aid and encouragement were never lacking. Acknowledgment 
is also made to Yandell Henderson, O. P. Hood, D. J. Parker, and 
J. W. Paul for criticisms and suggestions which were incorporated. 

EXPERIENCES OF FIRE FIGHTERS WHERE MASKS WERE 
INADEQUATE. 

New York City, pier fire .—Two men wearing Army masks were 
overcome while putting out a fire on a pier where sulphur was burning. 

Chicago, rag-shop fire .—One fireman while wearing an Army gas 
mask was overcome by products of combustion at a fire in a rag shop. 
He had been in the shop about 30 minutes and his condition was such 
that he was sent to the hospital. 

Detroit, celluloid fire .—Gas masks were found to give inadequate 
protection to firemen in a fire in a varnish factory in Detroit, Mich. 
Celluloid in the burning building gave off carbon monoxide and 
oxides of nitrogen. 

Experiments by the Bureau of Mines have shown that when cellu¬ 
loid burns in insufficient oxygen the gaseous products contain rather 


EXPERIENCES WHERE MASKS WERE USEFUL. 


5 


high percentages of carbon monoxide and oxides of nitrogen. If the 
supply of air is cut off entirely, the combustion may be continued by 
means of the combined oxygen contained in the celluloid itself. 
Chemical fire extinguishers are of slight value in fighting celluloid 
fires; water serves as well as anything. The Army gas mask will ab¬ 
sorb the oxides of nitrogen, but not the carbon monoxide in the gases 
produced. 

Rochester, N. Y ., basement fire. —The Rochester Democrat and 
Chronicle of June 19, 1919, described a fire at which firemen wearing 
Army masks were overcome. Firemen who entered the basement 
found that the dense smoke was mixed with ammonia from the re¬ 
frigerating plant and with illuminating gas from a broken pipe leading 
to a gas meter. Illuminating gas contains considerable proportions 
of carbon monoxide. Several men were overcome and one was so 
badly affected that he was taken to the fire house in an ambulance. 
About 20 men suffered from the effects of the gas in the basement, 
but most of them recovered shortly after they came out into the air. 
No one seems to have been seriously affected. 

EXPERIENCES WHERE MASKS WERE USEFUL. 

Pittsburgh, Pa., fire in waste-paper plant. —In contrast to the fore¬ 
going citations, masks of the Army type have proved useful at some 
fires, as was witnessed by one of the authors at a fire in the warehouse 
of the Pennsylvania Paper Stock Co., in Pittsburgh, Pa., July 1, 1919. 
The building had four stories, was of fireproof brick construction, 
and contained large quantities of baled scrap paper and rags. 
Twenty-one firemen were injured, most of whom were overcome by 
smoke and required hospital treatment. The building was venti¬ 
lated by breaking nearly all the windows. Under these conditions 
firemen wearing commercially produced gas masks of the Army type, 
equipped with filters in the canisters for removing smoke, were able 
to work in the worst part of the building, in shifts of 25 to 30 minutes 
each, for a period of five to six hours. Under the same conditions 
men without masks would work for five minutes, come to fresh air to 
rest and recuperate, and return to the work in the building for an¬ 
other five minutes, when they would come out with eyes swollen 
nearly shut by the smoke and so weakened that hospital treatment 
was necessary. 

Spring Lake, N. J., garage fire. —Four firemen wearing gas masks 
were able to work in a garage filled with smoke. 2 

New Brunswick, N. J., cellar fire. —At a very smoky cellar firemen 
wearing Army gas masks entered, ventilated the building, and 
located and extinguished the fire. 3 


* Letter of Chief C. H. Waters: Fire and Water Eng., vol. 65, Apr. 16,1919, p. 876. 

* Letter cf Chief H. J. Francis: Fire and Water Eng., vol. 65, Apr. 16,1919, pp. 876-877. 



6 gas Masks for gases met in fighting fires. 

Camden, N. J.,jire in wall-paper factory. —At a fire in the Hitchner 
wall paper plant, February 18, 1919, gas masks were used to get at 
the fire, and resulted in a saving of thousands of dollars. 4 

Moline, 111., fires in storerooms. —Two fires occurred in storerooms 
which filled with heavy thick smoke. Firemen wearing gas masks 
were able to enter the building and work with a line of hose. 5 

Duluth, Minn., fire in wooden dwelling. —The fire started in the 
basement of a wooden dwelling and had spread into the walls on the 
second story when the fire department arrived. An unprotected 
man was unable to enter the second story because of the smoke. The 
assistant chief, wearing an Army gas mask, entered the second floor, 
ventilated the place, and thus enabled the other men to work there. 6 

DISCUSSION OF THE EXPERIENCES. 

At the pier fire where sulphur was burning the firemen may have 
encountered sulphur dioxide gas in concentrations greater than the 
canisters could absorb completely. Besides this instance of the 
failure of an Army gas mask to protect its wearer against a high con¬ 
centration of a gas that is readily absorbed in lower concentrations, 
the Army masks are shown to give no protection against carbon 
monoxide and ammonia. 

Altogether, the examples show the wide variety of situations in 
which the gas masks have been used. An early discussion of the use 
of gas masks for fire fighting stated 7 that firemen are entering smoke- 
filled areas every day without the use of appliances, and, therefore, 
the gas masks offer protection of some value, as they are adapted for 
use in the great majority of fires. The instances cited previously 
where the gas mask has proved useful are few, but are varied enough 
to show the many different situations where gas masks are proving 
valuable aids to firemen. Probably thousands of gas masks are in 
use among the many fire departments of the country, so undoubtedly 
their usefulness has greatly increased. On the whole, the incidents 
show the usefulness of the gas mask to fire fighters, but demon¬ 
strate also that undue risks should not be taken with them. 

THE CHEMISTRY OF COMBUSTION. 

Probably the best way to analyze the value and limitations of the 
gas mask for fire fighting is to consider the process of combustion, 
the effect on man of the various products that are formed, and the 
action of the mask on these products. Ordinary pure, dry air con¬ 
sists chiefly of oxygen and nitrogen in the proportion of nearly four 

4 Letter of Chief P. B. Carter: Fire and Water Eng., vol. 65, Apr. 16,1919, p. 877. 

5 Letter of Chief J. Q. Hawk: Fire and Water Eng., vol. 65, Apr. 16,1919, p. 878. 

« Letter from First Assistant Chief C. W. Wilson: Fire and Water Eng., vol. 65, Apr. 16,1919, p. 878. 

7 Anon., Is the Army gas mask safe for fire fighting. Safeguarding America Against Fire, vol.ll March 
1919, p. 8. * » 



THE CHEMISTRY OF COMBUSTION. 


7 


volumes of nitrogen to one volume of oxygen. The nitrogen is an 
inactive gas and takes no part in combustion or in supporting life. 
It merely serves to dilute the oxygen and to reduce its activity. 

The important constituent of air is oxygen; without it there could 
be no life or combustion. Burning or combustion is the rapid union 
of oxygen with substances, the process being accompanied by the 
production of heat and usually of flame. If a lighted candle is placed 
in a glass fruit jar and the cap is closed air-tight, the flame will grad¬ 
ually become weaker and finally go out. Chemical analysis of the 
air left in the jar will then show a different composition from that 
of pure air. The percentage of oxygen will have decreased from 21 
to about 16 or 17 per cent, and in place of the consumed oxygen there 
will be from 3 to 4 per cent of another gas, carbon dioxide. 

A man placed in a small, tightly closed chamber will finally suffo¬ 
cate, like the candle in the jar, but he will retain consciousness until 
the oxygen is reduced to 12 or 13 per cent, if he is working, or to 10 per 
cent if he is at rest. Both the man and the candle flame require 
oxygen, and both give off carbon dioxide in its place. The oxygen 
combines with carbon, forming carbon dioxide and giving off heat 
by the union. In the wax or fat of the candle there is also hydrogen, 
which burns by uniting with the oxygen of the air and forms water 
vapor. Therefore, the products of combustion of a candle burning 
freely with plenty of air are carbon dioxide and water vapor. 

PRODUCTS OF COMPLETE COMBUSTION. 

These two gases—carbon dioxide and water vapor—are the prod¬ 
ucts of complete combustion not only of a candle but also of most of 
the common inflammable materials such as petroleum, natural and 
artificial gas, coal, wood, and paper. Coal, of course, contains some 
sulphur, which as it burns forms with oxygen a pungent suffocating 
gas called sulphur dioxide. No smoke is given off in absolutely 
complete combustion; neither are there any irritating or very poison¬ 
ous gases when the burning material is ordinary coal, wood, paper, 
or similar material. 

PRODUCTS OF INCOMPLETE COMBUSTION. 

Complete combustion without any visible smoke is infrequent. 
In the ordinary fire, especially before it gets well under way, there 
are many particles of carbon, in the form of soot and tar, which escape 
before they are burned. Smoke consists of these fine particles. 
Some of these tars are very irritating to the eyes and respiratory 
passages, and produce coughing and choking when inhaled. 

A much more serious product of incomplete combustion is a highly 
poisonous gas called carbon monoxide. This dangerous gas is like 
carbon dioxide, a combination of carbon and oxygen, but contains 


8 


GAS MASKS FOE GASES MET IK FIGHTING FIRES. 


only half as much oxygen. Hence, it is most likely to be formed 
when the supply of air to the fire is restricted, as in smoldering fires of 
closely packed materials in a basement or closed room where the air 
can not get at the fire. Although dense smoke oftentimes indicates 
dangerous quantities of carbon monoxide, it is by no means a sure 
guide. Many very smoky fires give off but little of this poisonous 
gas. 

Carbon monoxide is also produced by the distillation of coal, 
wood, and many other combustible materials. Such distillation 
may be seen when fresh coal is thrown on a hot fire. While the coal 
is heating, but not hot enough to burn, smoke and gas are seen com¬ 
ing off. One of these gases is carbon monoxide and the smoke is 
largely particles of tar. As the fresh coal becomes hotter, or when 
flame strikes the gases that are being distilled off, these gases ignite 
and burn. The carbon monoxide burns to carbon dioxide, the pro¬ 
duct of complete combustion. If a grate fire were kept smoldering 
without bursting into flame, and the fumes were allowed to dis¬ 
charge into a closed room, enough carbon monoxide would soon be 
generated to overcome a man. 

PROPERTIES AND EFFECT ON MAN OF VARIOUS PRODUCTS OF 
COMBUSTION. 

CARBON DIOXIDE. 

Carbon dioxide is a colorless and odorless gas, approximately 
one-half heavier than air. It is the principal product of complete 
combustion of carbonaceous materials and is also produced in the 
tissues and organs of the body when the carbon in the body, which 
comes originally from the food, unites with the oxygen of the air 
inhaled. A man’s breath contains about 4 per cent carbon dioxide. 
The flue gas from a boiler furnace contains from 8 to 14 per cent of 
this gas, and smaller proportions are found in the smoke from all 
fires. A resting man can breathe 2 per cent carbon dioxide in other¬ 
wise pure air for a period of several hours without ill effects. Three 
to four per cent carbon dioxide cause an oppressive feeling, and pro¬ 
duces shortness of breath or panting, especially if a man is working. 
Five to six per cent produces stronger panting, headache, flushing of 
the face, and, in fact, will soon exhaust a man so that he can not 
continue work. No subsequent ill effects, however, result. Higher 
percentages are asphyxiating. 

These data indicate that a man can withstand a considerable 
percentage of carbon dioxide, probably more than a fireman is 
likely to encounter in the smoke from any fire. The maximum 
percentage of carbon dioxide found in any of the experimental fires, 


EFFECT 0N MAN OF VARIOUS PRODUCTS OF COMBUSTION. 9 

which are described in a subsequent part of this paper, was 4.3 per 
cent. This amount wmuld not be serious unless breathed for periods 
of 30 minutes or more, and, furthermore, the Army gas mask or any 
similar mask containing a soda-lime canister would remove some of 
the carbon dioxide from the inhaled air. 

CARBON MONOXIDE. 

The following statements are taken from a paper by Dr. Hender¬ 
son. 8 

Carbon monoxide is formed by the incomplete combustion of car¬ 
bonaceous materials. It is extremely poisonous and is responsible 
for more deaths in civil life than all other gases combined. To it are 
chiefly due the poisonous effects of illuminating gas, producer and 
blast-furnace gas, the afterdamp of explosions in coal mines, and the 
products of combustion of fires. It has no odor, taste, or color, nor 
does it give any warning by irritating the eyes or throat. It is 
poisonous because it combines with the red coloring matter (haemo¬ 
globin) of the blood more readily than oxygen does, and oxygen is 
thus excluded. Consequently the victim dies of suffocation just as 
if his supply of air were shut off. A few breaths of air containing 2 
per cent carbon monoxide will cause unconsciousness and death 
almost as quickly as drowning. 

The effect of carbon monoxide on a man is proportional to the 
amount in the air and the length of time it is inhaled. A very low 
percentage breathed for a long period of time may saturate the blood 
to the same extent as a high percentage for a short time. Death is 
likely to ensue when, a man breathes air containing 0.2 per cent car¬ 
bon monoxide for four or five hours, or 0.4 per cent for one hour. 
These are rough figures only, as a man working vigorously breathes 
three to nine times as great a volume of air as a man at rest, and will, 
therefore, be overcome sooner. Different men also vary somewhat 
in their susceptibility to carbon monoxide poisoning. Burrell 9 
states that he was very sick for eight hours after exposing himself 
for a period of 20 minutes to an atmosphere containing 0.25 per cent 
of this gas. Relatively short exposures for 20 to 30 minutes to any 
percentage above 0.10 per cent must be regarded as dangerous to a 
man, even when he is not working. 

During the hasty and vigouous exertion of fighting fires, the vol¬ 
ume of breathing may increase to even eight times that during rest, 
and thus saturate the blood much faster with carbon monoxide. 
The firemen must, therefore, regard as dangerous an atmosphere 
containing percentages as low as 0.10 per cent, especially if he 

8 Henderson, Yandell, Carbon monoxide poisoning: Jour. Am. Med. Assoc, vol. 67,1916, pp 580-583. 

s Burrell, G. A. and Seibert, F. M., GaSes found in tio'al mines: Miners’ Circ. 14, Bureau of Mines, 1916, 




10 GAS MASKS FOR GASES MET IK FIGHTING FIRES. 

breathes this atmosphere for more than 10 minutes. The ordinary 
Army gas mask affords no protection from carbon monoxide. Special 
canisters capable of absorbing low percentages, up to 3 or 5 per cent, 
may become available in the near future. 

SYMPTOMS OF CARBON MONOXIDE POISONING. 

According to Foster and Haldane, 10 and to Henderson, * 11 the symp¬ 
toms of carbon monoxide poisoning are much the same as those 
produced by air from which the oxygen has been burned out, and 
differ according to the degree of saturation of the blood with the gas. 
With 20 per cent saturation, the only symptom is a slight tendency 
to dizziness and shortness of breath on exertion. As the saturation 
increases, however, the symptoms of want of oxygen become more 
and more pronounced, until at 50 per cent saturation a person is 
scarcely able to stand, and even slight exertion causes loss of con¬ 
sciousness. The effects of carbon monoxide are insidious. At 
first only a slight shortness of breath and palpitations are noticeable 
with hardly any discomfort; the senses and the power of judgment 
and of movement are commonly much impaired before the person is 
aware that anything is wrong. Sometimes the victim becomes 
much excited, but often he is simply drowsy and stupid. The 
symptoms are in some respects similar to those produced by alcohol. 
One curious fact is that in carbon monoxide poisoning, as in alcoholic 
poisoning, sudden exposure to cool, fresh air may greatly increase 
the symptoms. In many cases death seems to have been brought 
about immediately by muscular exertion, as in attempts to escape 
up ladders or inclines. If death is gradual, the haemoglobin (red 
coloring matter of the blood) is usually found to be 80 per cent 
saturated with carbon monoxide. Persons rescued in an uncon¬ 
scious state, after long exposure to carbon monoxide, often die later 
from damage to the system during exposure. 

The process of freeing the blood from carbon monoxide sets in 
when a man reaches fresh air, and if he breathes vigorously relief 
may proceed rapidly. The ill effects, however, do not pass off so 
rapidly, hut may persist for hours, days, weeks, or throughout life. 
Most of the harm has been done before the man reaches fresh air, 
and the ill effects may be manifest later. For this reason it is better 
to send fresh men into a place where carbon monoxide is suspected 
rather than men who have previously breathed the gas. 

DETECTION OF CARBON MONOXIDE. 

Mice and birds, preferably canary birds, are used by the Bureau 
of Mines rescue parties for detecting carbon monoxide, because these 

10 Foster, C. L. N. and Haldajnfej £T> SL .Tlie®yestigafti(Jn df mine air. London; 1905, pp. 146-^7. 

11 hendeVsotf, YantiSeft, CaVb 4 on mbnWde 'pworan^: JoW. Am. Med. £oc., Vol. 67,1*916, pp. 580-683. 



POISONOUS GASES ENCOUNTERED BY FIREMEN. 


11 


creatures are much more sensitive to the poisonous action of the gas 
than men. If an exploring party cautiously enters a suspected 
atmosphere with birds, it will be able to escape safely if it leaves 
promptly when the birds begin to show signs of distress. 

SOOT, TAR, AND SMOKE VAPORS. 

The choking, irritating effect of smoke is due to the finely divided 
particles of soot and tar and to certain smoke vapors, similar to for¬ 
maldehyde, that have an extremely irritating action on the eyes and 
throat. None of these substances are poisonous in the amounts in 
which they are found in smoke, but their immediate action on the 
throat, eyes, and lungs is so strong that they may easily disqualify 
the fireman from performing any effective work, and, in extreme 
cases, may so interfere with his breathing as to produce unconscious¬ 
ness. 

An Army type gas mask equipped with a canister containing cotton 
pads and activated charcoal will furnish protection against soot, tar, 
and smoke vapors, provided there is no carbon monoxide nor a 
deficiency of oxygen. The cotton pads filter out the soot and tar 
particles, and the charcoal absorbs the irritating smoke vapors. 

OTHER POISONOUS AND ASPHYXIATING GASES ENCOUNTERED 
BY FIREMEN. 

In addition to the common products of combustion of ordinary 
fires, a city fire department often has to contend with poisonous and 
asphyxiating gases and fumes from chemicals, broken illuminating 
gas mains, ammonia from refrigerating plants, and many substances 
such as motion-picture films, varnishes, and lacquers, that give off 
when burning large quantities of unusually dangerous fumes. 

OXIDES OF NITROGEN. 

When strong nitric acid acts on organic matter or certain metals 
in the presence of air, a reddish brown, insidiously poisonous gas is 
given off, a chemical combination of nitrogen and oxygen, called 
nitrogen peroxide. Several other oxides of nitrogen contain oxygen 
in different proportions, as, for example, nitrous oxide, which is the 
common “laughing gas” used by the dentist for the painless extrac¬ 
tion of teeth. This gas has a marked anaesthetic effect when inhaled 
in considerable quantity but is not very poisonous. The fire fighter 
is concerned chiefly with the brown nitrogen peroxide and the vapors 
of nitric acid, as these are the substances he occasionally encounters. 

Nitrogen peroxide is very likely to be met in a burning chemical 
plant or warehouse where nitric acid or certain nitrates are stored. 
Burning dynamitb, nitro pfoWders^ mDtibmpl'cture films, and celluloid 


12 


GAS MASKS FOR GASES MET IK FIGHTING FIRES. 


give off large quantities of these poisonous brown fumes. Thompson 12 
describes the following accidents in which men were overcome from 
nitrous fumes: 

A few years ago, a number of workmen were unloading from a vessel at a dock in 
New York carboys of nitric acid, some of which became accidentally broken. Their 
contents flowed over the wooden floor, producing dense clouds of acid vapor. The 
workmen were immediately overcome with suffocation, and in a few hours intense 
capillary bronchitis developed, which was fatal in several instances. The action of 
nitrous compounds upon wood evolves large quantities of vapor very rapidly. 

An unusual accident occurred in the Gunnison tunnel in 1911. A blast was ex¬ 
ploded and 13 men inhaled the smoke at some distance. In less than three days 
nine of these men died from acute inflammation of the lungs. It was found that 
nitrous fumes, consisting of nitrogen peroxide, had been developed from the powder 
smoke. 

Haldane 13 exposed mice to a concentration of 0.05 per cent of nitro¬ 
gen peroxide for one-half hour. Death followed in 24 hours. Guinea 
pigs and rabbits have been killed after six to eight minutes’ exposure 
to high concentrations. 

Hamilton 14 states that pneumonia may follow a case of poisoning 
in 1 to 30 days. Quickly fatal cases do not usually develop pneu¬ 
monia, but autopsy generally shows congestion of the finer bronchi¬ 
oles and air vesicles. 

Regarding nitrogen peroxide gas, Oliver 15 says: 

During inspiration of this gas there is a painful burning of the throat, which ceases 
when the fits of coughing have rejected the poison from the lungs. A few hours 
afterward, when it would seem as if all symptoms had ceased and all fear of possible 
complications had passed away, the individual who has breathed the gas begins to 
complain of severe compression of the chest and of inspiration being painful. There 
is profuse, foamy, yellow expectoration, the face becomes pale, the temperature ele¬ 
vated, the pulse frequent and small, and the patient succumbs without loss of his 
intellectual functions. After death, the lungs are found to be gorged with dark 
liquid blood, and are the seat of patchy hemorrhages, the bronchial tubes contain 
bloody foam, and the heart is filled with dark liquid blood. 

SULPHUR DIOXIDE. 

The burning of sulphur or brimstone in air produces a strongly 
irritating and pungent gas called sulphur dioxide. This gas is a 
chemical combination of sulphur and oxygen and is not nearly so 
poisonous as carbon monoxide or nitric fumes. There is very little 
danger from sulphur dioxide poisoning, because the fumes are so irri¬ 
tating to the eyes and throat that the victim is compelled to seek 
air at once. In very strong fumes, when the victim can not avoid 
breathing them, death may result from respiratory spasms and as- 

12 Thompson, M. D., and Gilman, W., The occupational diseases. New York, 1914, p. 374. 

13 See Irvine, R. G., Gassing accidents from fumes of explosives: Brit. Med. Jour., vol. 2,1916, pp. 162-163. 

14 Hamilton, M. A., Industrial poisons used or produced in the manufacture of explosives: U. S. Bur. 
Labor Stat., Bull. 219,1917,141 pp. 

is Oliver, Thomas, Diseases. of occupation. London, 2d ed., 1908, p. 277. 




POISONOUS GASES ENCOUNTERED BY FIREMEN. 


13 


phyxia. Ordinarily, however, exposure to mild fumes merely pro¬ 
duces headache, coughing, smarting of the eyes, and later constric¬ 
tion of the chest and bronchitis. 

Most persons detect sulphur dioxide by the smarting of the eyes 
and irritation of the throat, when the proportion present is only 5 
to 20 parts in a million parts of air; 500 parts to a million parts of 
air, or 0.05 per cent sulphur dioxide, is so acutely pungent as to 
cause a sensation of suffocation, even with the first breath. 

Sulphur dioxide fumes are likely to be met in sulphite paper mills, 
sulphuric acid plants, smelters, chemical plants and stores. Most 
persons can recognize the gas by its odor, with which they have be¬ 
come familiar through the use of burning sulphur for fumigation or 
disinfection. The Army mask affords good protection, unless the 
fumes are very dense, as in the previously cited fire on the docks in 
New York City (p. 4), where large quantities of sulphur burned. At 
this fire, it was reported that the fumes penetrated the Army masks. 
There are now on the market, however, masks provided with special acid- 
gas canisters that are more effective than the original Army canisters. 

AMMONIA. 

The widespread use of ammonia refrigerating plants make it neces¬ 
sary that city fire departments have adequate protection from this 
irritating gas, not only to cope with fires in buildings containing 
refrigerating plants, but also to enter rooms in which ammonia is 
escaping, and to shut off the valves of the container or apparatus from 
which the gas is leaking. 

In the pure form, ammonia is a colorless gas and has a sharp, 
penetrating odor. Under high pressure it can be condensed to 
a liquid. When the pressure on a tank of liquid ammonia is 
released the liquid evaporates into, a gas again. Much heat is 
absorbed in the process of evaporation and the cooling effect is 
utilized in refrigerating and artificial-ice plants. The tempera¬ 
ture of liquid ammonia when exposed to the air is 37° F. below 
zero, so if any part of the human body comes in contact with 
the liquid it may be frozen. Should a leak occur in the ammonia¬ 
piping system of a refrigerating plant, the ammonia, being under 
pressure, would escape and fill the room with gas. As the gas is 
very soluble in water, it may be removed from the air of a room not 
easily ventilated by spraying the air thoroughly with water. In 
ammonia gas a handkerchief or cloth wet with water and used as a 
respirator over the mouth and nose of the fireman, if he is caught 
without other protection, serves to remove much of the gas from the 
air breathed. The spraying of water from a hose over the neighbor¬ 
hood of the leak also absorbs much of the gas and gives protection. 

55299°—21-2 


14 GAS MASKS FOR GASES MET IN FIGHTING FIRES. 

Ammonia is not considered very poisonous, as it does not often 
produce death when inhaled. It is, however, quite irritating to the 
eyes, throat, and lungs in concentrations less than 1 part of ammonia 
to 1,000 parts of air. According to Lehman, 16 0.03 per cent ammonia 
in air can be inhaled from one-half to one hour without producing 
serious disturbances. Under the same conditions, 0.3 to 0.5 per cent is 
considered dangerous. The inhalation of larger percentages may cause 
a spasmodic closing of the glottis and asphyxiation of the victim 

Experiments at the American University experiment station show 
that the average man will detect the odor of ammonia when only 
0.005 per cent is present in air; the eyes are irritated when the per¬ 
centage is over 0.07 per cent and throat irritation begins at 0.04 
per cent; coughing is produced by 0.17 per cent. These percentages 
differ for different persons, as individual sensitivity is not the same. 

The standard Army gas mask as issued for military purposes does 
not provide sufficient protection from ammonia for industrial use or 
for fire departments. Special ammonia canisters, however, that give 
complete protection to the eyes and the lungs can now be purchased from 
commercial supply houses In fact, a fireman wearing an approved 
ammonia mask need have no hesitancy in entering any atmosphere 
containing ammonia fumes which is bearable as regards skin irrita¬ 
tion. Two per cent ammonia is about the maximum strength that a 
man’s skin will endure; more than this has an intolerably irritating 
action on the tender parts of the body, which increases with the con¬ 
centration. Perspiration accentuates the effect. Exposure of the 
skin sufficiently long will cause blistering. 

TREATMENT FOR AMMONIA POISONING. 

For alleviating the effects of ammonia on the skin use lint or linen 
or washed muslin wet with picric acid or the picric acid gauze supplied 
with first-aid outfits. 

To treat the eyes first pour a saturated solution of boric acid into 
the eyes, or use the solution with an eye cup. Have the patient 
open and close the eyes rapidly to bring the solution in contact with 
the entire inner surface. 

When ammonia gas has been inhaled, dip a handkerchief or gauze, 
folded once, into vinegar, wring out lightly, and lay loosely over the 
month and nose. 17 If liquid ammonia has entered the nostrils, 
sniff up some diluted vinegar and apply sweet oil to the inner surface 
of the nostrils. If ammonia has been swallowed, have the patient 
suck lemons, or give diluted vinegar, and follow with four teaspoons 
of sweet oil, milk, or the whites of three or four eggs and ice. If 
vomiting occurs, aid it with liberal draughts of lukewarm water. 


^Lehman, K. B., Table of poisonous gases, in Roberts’ Praktische Toxikologie. Stuttgart, 1912. p. 45. 
m National Ammonia Co., New York, N. Y. 



POISONOUS GASES ENCOUNTERED BY FIREMEN. 15 

CHLORINE. 

Chlorine was the first poisonous gas used on a large scale in the 
World War. Great clouds of this suffocating gas were sent against 
unprotected Canadians at Ypres with terrible effect. At ordinary 
temperatures chlorine is a greenish-yellow gas. However, it can be 
liquified by compressing it into steel cylinders similar to those used 
for transporting oxygen gas for welding and cutting iron and steel. 
Considerable quantities of liquid chlorine are transported in this 
form for commercial uses, especially for treating city water supplies 
to kill bacteria, for recovering tin from scrap tin plate, for bleaching 
linen, cotton, and paper, for use in laundries, and for manufacturing 
disinfecting agents and many other chemicals. 

If exposed to fire, a cylinder containing liquid chlorine would be 
very likely to blow out a fusible metal plug on its stem. This would 
release the gas to add to the difficulties of fire fighters, as the suffo¬ 
cating action of the chlorine is intolerable, even in very small amounts. 
The breathing of air containing only 0.004 to 0.006 per cent chlorine 
for a period of 30 minutes to 1 hour is dangerous to life. A few deep 
breaths of air containing 0.1 per cent chlorine is likely to prove fatal. 
Lehman 18 gives 0.0004 per cent, or four parts of chlorine in a million 
parts of air, as the maximum percentage that a man can inhale for 
30 minutes to 1 hour without serious effects. 

Chlorine, when inhaled, even in small quantities, has a strongly 
irritating action on the mucous membrane of the lungs and respiratory 
passages. In cases of severe poisoning, the lungs become congested 
and the victim develops a condition similar to that of pneumonia. 
Death may result several days after exposure to the gas. 

As chlorine is more than twice as heavy as air, firemen should 
observe especial care in entering basements of buildings in which 
this gas has been released. If there are no strong air currents, chlo¬ 
rine gas will flow to the lowest places and fill depressions in much the 
same way as water. 

The ordinary Army gas mask affords excellent protection against 
chlorine in the concentrations likely to be encountered in burning 
chemical plants or warehouses. 

ILLUMINATING GAS. 

Broken illuminating or artificial gas pipes sometimes add to the 
dangers of fire fighting, an excellent illustration being the Rochester, 
N. Y., fire previously described in this paper (p. 5), where a number 
of firemen wearing Army gas masks were overcome. In this fire the 
dangerous constituent of the gas which penetrated the mask was 
probably carbon monoxide. Practically all artificial illuminating 
gas contains carbon monoxide. The percentage varies from 6 to 35 


w Lehman, K. B., Table of Poisonous Gases, in Robert's Praktische Toxikologie. Stuttgart, 1912, p. 45. 



16 


GAS MASKS FOR GASES MET IN FIGHTING FIRES. 


per cent, according to the proportions of coal gas and water gas that 
are put into the gas by the manufacturer. Pure water gas contains 
about 35 per cent carbon monoxide, pure coal gas about 6 per cent. 

The Army type of gas mask and the ordinary commercial smoke 
masks do not protect against carbon monoxide. For this purpose, 
an oxygen-breathing apparatus should be used, at least until the new 
carbon monoxide mask that is being developed by the Government 
is available. 

Where unconsciousness occurs from the breathing of illuminating 
gas or carbon monoxide in any form, resuscitation by the Schaefer 
method should be used. 

GASOLINE AND PETROLEUM VAPORS. 

As regards fire fighting, gasoline and other petroleum vapors are of 
interest chiefly because of their great inflammability and the fact 
that only 1| per cent of gasoline vapor mixed with air will explode on 
ignition. The explosive range is 1.4 per cent to 6 per cent. Fire¬ 
men will be interested, however, in the facts regarding the danger 
from inhaling these vapors, as they may be called upon to rescue 
some one who has been overcome on entering an empty gasoline tank. 

Benzine and gasoline are the more volatile parts of crude petro¬ 
leum. Owing to their low boiling points, these liquids evaporate 
very quickly on exposure to air. The air space of a closed gasoline 
tank having some liquid gasoline left in the bottom contains much 
gasoline vapor mixed with the air. If the day is very hot, or the 
sides of the tank become heated, the percentage of gasoline vapor in 
the air becomes high enough to render unconscious quickly a man 
who breathes it. Men have thus been overcome on inhaling air from 
open trapdoors in the top of crude oil or gasoline storage tanks. 
Similar danger from petroleum gases attends the cleaning out of 
empty tank cars and storage tanks. A considerable quantity of gas 
may be left in the car or tank, especially if much sludge must be 
stirred up in cleaning, thus setting free more gas. To get rid of these 
hrespirable gases, in common practice, tanks and stills are thor¬ 
oughly steamed out before workmen are sent into them. Even after 
this has been done, frequently so much gas is left that men can work 
only in short shifts, usually not longer than 10 minutes. 

The inhalation of benzine, gasoline, and other volatile vapors given 
off from petroleum, causes headache, dizziness, and frequently an 
intoxication in which the victim becomes excited and hysterical. 
Experiments carried out by the Bureau of Mines 19 have shown that 
the odor of gasoline is noticeable in inhaled air at a concentration of 
0.03 per cent; a man who breathed gasoline vapors in air, increasing 
in concentration from 0.07 to 0.28 per cent for 14J minutes, felt dizzy at 

i® Fieldner, A. C., Katz, S. H., and Kinney, S. P., Permeability of oxygen breathing apparatus to gaso¬ 
line vapors: Technical Paper 272, Bureau of Mines, 1921, 24 pp. 



POISONOUS GASES ENCOUNTERED BY FIREMEN. 


17 


the end; a concentration of 1.13 to 2.22 per cent for three minutes 
made a man so dizzy that he had to hold to a table to stand; with a 
concentration increasing from 2.22 to 2.60 per cent a man became 
dizzy after only 10 or 12 breaths. Lehman 20 gives 15 to 25 milli¬ 
grams of gasoline to a liter of air, corresponding to 0.13 to 0.71 per 
cent, as the maximum that can be inhaled from 30 minutes to one 
hour without serious disturbances. High concentrations of gas 
quickly overcome the victim, causing complete insensibility and 
occasionally death. In most cases, however, the patient recovers as 
soon as he is removed to fresh air. The Schaefer prone pressure 
method of resuscitation should be used if breathing is shallow. Re¬ 
covery is usually accompanied by severe headache and sometimes 
nausea. 

Ordinary Army gas masks afford some degree of protection against 
low concentrations of petroleum vapors and gasoline for such short 
periods of time as five to ten minutes. A canister filled with acti¬ 
vated charcoal has a higher capacity for these gases and is, therefore, 
safer to use than the Army canister, which has only 60 per cent char¬ 
coal. But even with this canister tanks should be entered cau¬ 
tiously as the gas may be too concentrated for any gas mask. An air 
helmet or oxygen breathing apparatus affords better protection than 
gas masks. 

Recent experiments in the Bureau of Mines laboratory have shown 
that many of the thin, rubberized-cloth breathing bags on oxygen 
breathing apparatus are permeable by gasoline and similar vapors. 
Low concentrations of gasoline vapor, such as are found in tanks 
containing ordinary motor gasoline, are not likely to penetrate the 
bags enough to be dangerous during periods of 15 to 30 minutes; but 
high concentrations, such as the vapors of more volatile distillates or 
casing-head gasoline, may permeate some bags fast enough to cause 
dangerous quantities of the vapor to accumulate in the breathing 
bag. Breathing bags of the thick rubber type have proved quite 
impermeable in a two-hour test. 

At certain refining plants, the Tissot type of gas-mask face pieces 
attached to a long, flexible hose leading to pure air have been suc¬ 
cessfully used. A description of this type of air mask appears on 
page 21 of this bulletin. All things considered, it may be the best 
form of apparatus for use in gasoline vapors. Whether such an air 
helmet or an oxygen apparatus is used, the wearer should always 
have a stout rope attached to his person so that he can be removed 
immediately from the irrespirable atmosphere if anything goes 
wrong with his apparatus. 


20 Lehmann, K. B., Tabelle der kleinsten Mengen schadlicher Febrikgase, welche noch giftig sind und 
der Mengen, welche allenfalls ertragen werden: in book by Rudolf Robert, Kompendium der praktischen 
Toxikologie zum Gebrauche fur Arzte, Studierende und Medizinalbeamte. Stuttgart, 1912, p. 45. 



18 GAS MASKS FOR GASES MET IN FIGHTING FIRES. 

ACID AND MISCELLANEOUS CHEMICAL VAPORS. 

Fires in industrial plants that use acids and other chemicals, and 
in warehouses where such materials are stored, present many hazards 
to the firemen who have to enter the fume-laden atmosphere. The 
fumes from the two most common acids, hydrochloric, sometimes 
called muriatic acid, and sulphuric, although choking and irritating 
in the concentrations likely to be found in fires, are seldom fatal. 
Hydrochloric-acid gas is described on page 19. Nitric acid gives off 
highly poisonous brown fumes, which have been discussed under 
‘‘Oxides of nitrogen” (p. 11). In general, inhalation of strong acid 
fumes corrodes the delicate mucous membranes that line the respira¬ 
tory passages and the lungs, and if the corrosive action on the lungs 
is strong, death may follow from pneumonia. 

The Army type gas mask affords good protection against all ordi¬ 
nary concentrations of acid fumes. Failure or exhaustion of the 
mask is readily detected by irritation when the fumes penetrate the 
canister. 

Another class of gases, called the organic vapors, are similar in 
many respects to the vapors of gasoline and petroleum. They are 
absorbed by gas masks fitted with canisters that contain activated 
charcoal, providing the concentration is not excessive. The chief 
organic vapors that firemen may meet are those of benzene, carbon 
disulphide, carbon tetrachloride, formaldehyde, turpentine, and 
solvent naphthas. These liquids are largely used in the manufacture 
of rubber, explosives, dyes, paints, varnishes, and chemicals. Like 
the vapor of gasoline, organic vapors are generally inflam m able, and 
when mixed with air may cause violent explosions. 

Other organic vapors than those mentioned above may sometimes 
be encountered. Among these are acetone, alcohols, aniline, chloro¬ 
form, ether, and toluene. The Army gas mask affords protection 
against these. 

GASES FROM CARBON TETRACHLORIDE FIRE EXTINGUISHERS. 

At ordinary temperatures carbon tetrachloride is a volatile, sweet¬ 
smelling, colorless liquid. It readily vaporizes and the vapor is 
colorless and heavy; 7 to 9 per cent of the vapor mixed with air will 
extinguish fires. The heavy vapor tends to settle to the bottom of a 
room and form a blanket over the floor. This blanketing effect of the 
vapor on any material wet with carbon tetrachloride excludes air 
and so aids in extinguishing fires. Small fire extinguishers, holding 
about a quart of carbon tetrachloride, are widely used for extinguish¬ 
ing small or incipient fires and are very effective. 

There is danger from inhaling the gases formed by carbon tetra¬ 
chloride when sprayed on heated materials. Experiments by the 


POISONOUS GASES ENCOUNTERED BY EIREMEN. 


19 


Bureau of Mines, which are described later, have shown that the 
decomposition products of carbon tetrachloride may consist of 
phosgene, chlorine (sometimes), and hydrochloric (muriatic) acid 
gas. In addition, high concentrations of carbon tetrachloride itself 
are produced. Death may be caused by breathing the gases for only 
a short time. Danger is greatest when the fire is in a closed or con¬ 
fined space. The Army gas mask protects the wearer in any concen¬ 
trations likely to be met. 

Of the gases produced by carbon tetrachloride on fires, chlorine 
has been described previously. The others, phosgene and hydro¬ 
chloric-acid gas, are considered below. 

PHOSGENE. 

Phosgene, as one of the gases most used in warfare, has been 
studied quite thoroughly. Aside from that formed from carbon 
tetrachloride in fires, firemen are not likely to meet phosgene, for its 
use in the chemical industry is small. 

It has been found 21 that three parts of phosgene in a million parts 
of air, irritate the throat; five parts cause coughing; six parts can be 
detected by smell; 25 parts per million is the approximate deadly 
concentration for an average man when exposed for 30 minutes. 

HYDROCHLORIC-ACID GAS. 

Hydrochloric-acid gas has a pungent, biting odor, and although it 
irritates the respiratory passages, it is not considered very toxic; 
but brief exposure to a concentration of 1,000 parts per million, or 0.1 
per cent, of the gas has been known to cause death. 22 

Hydrochoric-acid gas, besides being produced from carbon tetra¬ 
chloride in fires, is one of the acids most used in the industries, where 
it is commonly known as muriatic acid, which is a solution of large 
quantities of the gas in water. When heated, the gas is driven off 
from the solution. As muriatic acid is widely used, firemen may 
encounter the gas at many fires. The Army gas mask offers effective 
protection. 

CARBON TETRACHLORIDE. 

Undecomposed carbon tetrachloride vapor arising from the use of 
the liquid in fire extinguishers when encountered in a small confined 
space will probably produce unconsciousness by its anaesthetic effect. 
The commercial product usually contains some carbon bisulphide, a 


21 Chemical Warfare Service, American University experiment station, Washington, D. O. 

22 Thompson, W. G., The occupational diseases. 1914, p. 370. 



20 


GAS MASKS FOE GASES MET IK FIGHTING FIEES. 


residue of the carbon bisulphide used in the manufacture. Waller 
and Veley 23 found that the presence of carbon bisulphide vapor 
with that of carbon tetrachloride greatly increased the toxicity, but 
comparatively large amounts of the carbon tetrachloride vapor must 
be breathed before the effects become dangerous. For this reason, 
the more serious danger in the use of carbon tetrachloride lies in the 
products formed from it rather than from the vapor itself. 

Lehman 24 states that 159 parts per million (0.016 per cent) will 
cause slight symptoms when breathed for several hours; 3,980 parts 
per million (0.4 per cent) may be inhaled for about one hour without 
very serious effects; 23,850 parts per million (2.4 per cent) are danger¬ 
ous in 30 minutes. 

An employee of the Bureau of Mines was overcome while using a 
carbon tetrachloride fire extinguisher on an automobile burning in 
the open air. Two employees of the Navy Department died as the 
result of breathing fumes from carbon tetrachloride that had been 
used when the clothes of one of them caught fire while the men were 
working in a very small compartment. 

The Army gas mask will protect the wearer against carbon tetra¬ 
chloride, and its use is recommended when a fire extinguisher of this 
type is used in a small, unventilated space. 

TYPES OF BREATHING APPARATUS. 

SELF-CONTAINED OXYGEN BREATHING APPARATUS. 

Self-contained oxygen breathing apparatus have been used ex¬ 
tensively by the engineers of the Bureau of Mines in fighting mine 
fires and in rescuing miners trapped by fire or by the poisonous gases 
resulting from fires and explosions. J. W. Paul, 25 describes these 
devices and the care that is necessary to keep them in serviceable con¬ 
dition. Plate I shows the Gibbs apparatus developed by the Bureau 
of Mines. It weighs about 34 pounds, and contains oxygen enough 
to supply a man at work for two hours or more. Plate II shows the 
Fleuss or Salvus light apparatus, which weighs about 15 pounds 
and holds oxygen enough to supply a man for about one-half hour. 

These apparatus will support life and enable one to work in any 
gas that does not attack the skin. Goggles are worn to protect the 
eyes. As the apparatus supply their own oxygen, the wearers are 
not dependent on the surrounding atmosphere. 

23 Waller, A. D., and Veley, G. A., Relative toxicities of chloroform and carbon tetrachloride: Jour. 
Am. Med. Asso. vol. 53 ,Aug. 28, 1909, p. 9. 

24 Lehman, K. B., Table in Roberts Praktische Toxikologie, Stuttgart, 1912, p. 45. 

as Paul, J. W., The use and care of mine rescue breathing apparatus: Miner’s Circular 4, Bureau of Mines, 
1912, p. 24. See also Oxygen mine rescue apparatus and physiological effects on users, byHenderson 
Yandell, and Paul, J. W., Tech. Paper 82, Bureau of Mines. 



BUREAU OF MINES TECHNICAL PAPER 248 PLATE 







BUREAU OF MINES 


TECHNICAL PAPER 248 PLATE II 


SALVUS LIGHT APPARATUS; SUPPLIES OXYGEN FOR HALF AN 
HOUR AND WEIGHS ABOUT 15 POUNDS. 




TYPES OF BREATHING APPARATUS. 


21 


“PIG SNOUT” RESPIRATORS. 

Plate III, A, shows a “ pig snout ” respirator, which contains a moist¬ 
ened sponge through which the inhaled air passes. Chemical solutions 
for absorbing gases may be used in the sponge, which also acts as a fil¬ 
ter to remove some dust and smoke particles. It is doubtful whether 
this type of respirator is more effective than a moistened handker¬ 
chief tied over the mouth and nose, or certain homemade respirators of 
muslin or cheesecloth, several layers deep and fashioned to fit the 
face. 26 Plate III, B, shows a similar respirator, which contains a paper 
filter, through which the air passes. This respirator filters out some 
dust and smoke, but will not remove any gases. 

AIR MASKS AND HELMETS. 

Air masks and helmets, which provide the wearer with fresh air 
through a long hose somewhat after the fashion of divers helmets, 
are made in many forms. Plate IV shows a mask that covers the face 
only. Pure air at some distant point is forced by a pump through the 
line of hose that leads into the mask. The hose is fastened to a belt 
which takes the pull necessary to move it after the wearer. The air, 
which enters the mask, passes out through a valve that prevents 
passage in the reverse direction. Also, with a Tissot face piece it 
is possible to use, instead of the absorbent canister, a noncollapsible 
hose leading to pure air. A f or | inch hose fitted with a check valve 
near the mask may be used without an air pump, provided the length 
of hose does not exceed 50 feet. In longer lengths the resistance 
becomes too high. 

Such use of a Tissot type gas mask with a line of hose replacing 
the absorbent canister is described by J. D. James, 27 safety inspector 
of the New Jersey Zinc Co., Palmerton, Pa. 

Tissot masks connected up with 50 feet of f-inch rubber hose, having 
a 6-inch funnel held in pure air on the other end, were according to 
Mr. James— 

Thoroughly tried out at the blast furnaces and gas producers of the New Jersey 
Zinc Co. plant at Palmerton with good results. One of the tests was to throw a 3-foot 
slide damper on the main gas line, where thirty-six f-inch bolts had to be removed 
before the slide could b£ opened to clean out the gas line. After cleaning the gas line 
the slide was closed and the 36 bolts replaced, tightened, and the joints sealed all around 
with clay. This test was made by two men who were enveloped with carbon monoxide 
about 45 minutes. After the job was completed both men declared that they 
were not affected in the least with gas, and continued their regular routine of work. 
Several tests have been made with the same very gratifying results. 

26 Anonymous, A simple and inexpensive respirator for dust protection: Bull. 90, Division of Industrial 
Hygiene, Department of Labor, State of New York, December, 1918,10 pp. 

*7 James, J. D., Experiments with the Tissot gas mask: Safety Eng., vol. 38, 1919, pp. 148-150. The 
accompanying photographs were reproduced through the courtesy of Mr. James. 



22 


GAS MASKS FOR GASES MET IN FIGHTING FIRES. 

The old way of turning these slide dampers always took at least six men working in 
pairs, each pair working at alternate periods, often only a few minutes each, and usually 
taking about one and one-half hours to do the job. Quite frequently some of the men 
were overcome with the gas, necessitating artificial resuscitation to relieve their con- 

dition. , 

The strongest argument in favor of this gas mask is that the men will not do this work 

now without this mask. 

Fifty feet is probably the greatest length of hose through which 
a man can comfortably breathe; beyond this length the resistance 
becomes so great that a pump should be used to force a continuous 
stream of air to the face, at a rate of 80 to 100 liters (3J cubic feet) 

per minute. | 

In using an air mask without a pump, a check valve should be 
placed in the air line within a few feet of the face piece to prevent the 
exhaled air from going back into the air line. An excellent plan is 
to attach a special metal coupling containing this check valve to a 
belt at the waist of the wearer. The flexible hose connection to the 
mask is attached to one end of this valve coupling and the 50-foot air 
hose to the other end. The radius of use of air masks and helmets is 
limited by the length of hose attached, which determines the dis¬ 
tance from pure air. In general, the longest practicable length of 
hose is about 100 feet. Air masks are well adapted for cleaning tanks 
containing irrespirable vapors and for similar work. Their useful¬ 
ness is reduced by the fact that the hose is cumbersome and when 
used with air pump an extra man is required to work the pump. 
Air helmets^ are much used in sand blasting and similar very dusty 
work, where the pure air supply may be obtained from an air- 
pressure line. 

DESCRIPTION AND PROPERTIES OF THE UNITED STATES ARMY TYPE 
OF GAS MASKS. 

CONSTRUCTION. 

American soldiers at the time of the signing of the armistice were 
supplied with a mask known as the R. F. K., which had a face piece 
of rubberized fabric. This mask is pictured in Plate V, A, and the 
details are given in figure 1. The nonshattering eyepieces had metal 
frames in order to make their insertion in the fabric gas-tight. At¬ 
tached to the interior of the mask was a mouthpiece, through which 
air was breathed, and a nose clip that prevented inhalation through 
the nose. This type of mask is familiar to most persons. However, 
as an improved face piece, shown in Plate V, B, had been developed 
and was being produced in quantity shortly before the armistice 
was signed, and is used also in masks now produced commercially, 
the R. F. K. will not be considered further. 

The newer type of face piece or mask is known as the Tissot type 
and is so designed that the wearer may breathe through his nose in 


BUREAU OF MINES TECHNICAL PAPER 248 PLATE II 




PIG SNOUT” RESPIRATOR CONTAIN- B. ‘‘PIG SNOUT” RESPIRATOR WITH PAPER FILTER 

ING A MOISTENED SPONGE. FOR DUST AND SMOKE. 











TECHNICAL PAPER 248 PLATE IV 




















TYPES OF BREATHING APPARATUS. 


23 


normal fashion. The mask is made of a stockinette-covered rubber 
of sufficient thickness to prevent collapse during the suction from in¬ 
halation. Large eyepieces, set close to the eyes, afford a wide angle of 
vision. Purified air from the canister passes through a rubber tube— 
corrugated to prevent collapse and to increase flexibility-into the 
space between the face and the mask. This fresh, relatively dry air 
as it is drawn into the mask, passes over the eyepieces and prevents 
fogging by the condensation of the moisture in the exhaled air. 
Exhaled air passes from the nose downward, and is discharged 
through a flutter valve, which allows passage in the exit direction only. 
When this mask is properly 
adjusted to the face, it is 
fairly comfortable, and the 
leakage of unpurified air is 
negligible. 

The canister that con¬ 
tains the absorbent mater¬ 
ial is carried in a haver¬ 
sack that hangs from the 
neck, as shown in Plate V, 

C. Figure 4 (p. 33) pictures 
the standard United States 
Army canister and the de¬ 
tails of its construction. 

The capacity of this canis¬ 
ter is 42 cubic inches of 
absorbent, which is a mix¬ 
ture of 60 per cent by vol¬ 
ume of activated charcoal 
and 40 per cent by volume 
of permanganate soda 
lime, both sized to pass 
through a screen of eight meshes to the inch and be retained 
on a screen of 14 meshes to the inch. Canisters for indus¬ 
trial use need not be limited to 42 cubic inches of absorbent. 
In fact, because of its longer life, a canister to hold 100 cubic inches 
or more would be of advantage for many industrial purposes. For 
other purposes, where only short life is needed, smaller canisters are 
desirable. Plate VI shows a small canister with mouthpiece directly 
attached; it is supported by the teeth, and a nose clip is used. This 
type was used for emergency purposes by some men working with 
poison gas during the war. The two filters (fig. 2) of cotton wool wad¬ 
ding in the U. S. Army canister are capable of filtering out the coarser 
dust and mist particles, but very finely divided particles, such as tobacco 
smoke, pass through the canisters to some extent. As will be shown 



Figure 1.—Details of the R. F. K. mask. 










24 


GAS MASKS FOR GASES MET IK FIGHTING FIRES. 


later, the canisters remove the smoke from ordinary wood fires. The 
rubber disk valve at the bottom allows air to how through the canister 
in one direction only. The heavy spring pressing on the stiff wire 
screen at the top holds the granular absorbent firmly in position. 
Corrugations on the tinned iron container add stiffness to the can, 
and tend to prevent the passage of gas along the walls. 



Figure 2.— Apparatus used for ma king smouldering fires: a, Sprinkler; b, coarse wire basket; c, can; 
d, hole in can; e, bricks; /, asbestos; g, fan. 


The canister itself is comparatively inexpensive, so that when 
the absorbent is exhausted it can be replaced by a new one at small 
cost. 

CARE AND INSPECTION OF GAS MASKS. 

Masks are constructed largely of rubberized fabric. Rubber 
deteriorates under the action of light and air, and the higher the 
temperature the more rapid is the deterioration. Fabric deteriorates 
if allowed to remain moist. Hence, masks should be kept in cool 







































BUREAU OF MINES TECHNICAL PAPER 248 





MASK USED BY THE U. S. ARMY. B. AIR MASK SUPPLIED WITH FRESH C. TISSOT TYPE OF U. S. ARMY GAS 

AIR THROUGH LONG HOSE. MASK. 















BUREAU OF MINES 


TECHNICAL PAPER 248 PLATE VI 



SMALL CANISTER WITH MOUTHPIECE DIRECTLY ATTACHED, 
SUPPORTED BY THE TEETH. 





TYPES OF BREATHING APPARATUS. 


25 


places where there is no excess moisture, and should be protected 
from light and air. Manufacturers provide cases or boxes in which 
to keep them, and the masks will last many times longer in the cases 
than outside. It is impossible to state the life of masks stored 
without use, as for instance, ammonia masks kept for emergencies; 
but it is believed that when properly stored they will retain their 
usefulness at least two years. After a mask has been used, it should 
be cleaned and dried before being put away. When masks are used 
by different persons, it is advisable to clean and disinfect them be¬ 
tween times. The Bureau of Mines recommends that the masks, 
separated from the canister, be immersed and washed in a 2 per cent 
solution of lysol, and then dried in the open air, with the lysol solu¬ 
tion adhering. Masks of the mouthpiece type should always be dis¬ 
infected at intervals even if worn by only one person. Sharp folds 
and creases are to be avoided in putting away masks. 

The eyepieces should be kept clean, preferably by rubbing the 
glass with a small piece of pure soap and then cleaning with a soft 
cloth; blowing the breath upon the glass will supply moisture for 
the purpose. Soldiers were provided with a small piece of soft cot¬ 
ton flannel for cleaning the glasses. Clean glass has less tendency to 
fog from moisture and permits better work. 

Canisters should be protected, especially from dampness and an¬ 
on the inside, and should be kept cool. The manufacturers send 
them out with plug seals covering the bottom valve opening, and 
with corks closing the hose nipple, unless the latter are attached to a 
mask. When completely protected from the action of outside air, 
canisters should last for years; but when free access of outside air is 
allowed, they may deteriorate rapidly, especially canisters containing 
soda lime, the absorbent for acid gases. Extra canisters should be 
kept on hand to replace those worn out by use. The purpose of a 
canister is marked on it by the manufacturer. Before using a canis¬ 
ter one should always read the inscription to see that the canister 
is suited for the gas in which it is to be worn. 

The life of a canister in various uses can not be foretold, because 
it depends on the concentration of the gas encountered and the 
volume of gas passed through. When a man works vigorously, as 
in walking miles in an hour, he breathes about 32 liters of air a 
minute. During intense exertion he may breathe 60 or 80 liters a 
minute or much more. When he is at rest, he breathes only 7 or 8 
liters per minute. Canisters in continuous use under a wide variety 
of circumstances in industries have shown lives varying from a few 
hours to many weeks. Likewise, it is impossible to tell the residual 
life of a canister after use without testing it against gas, which spoils 
it for further use. Resistance to the flow of air may indicate the 
probable life. At a flow of 85 liters per minute, the resistance of 


26 GAS MASKS FOR GASES MET IN FIGHTING FIRES. 

fresh canisters is about 3-J inches of water column or less. If the 
resistance increases to more than 4 inches, the canister has probably 
failed. But this test has not much practical importance, because 
of the special, rather complicated apparatus necessary and because 
the resistance does not change markedly in every canister. When 
a canister has been wet with water on the inside, it should not be 
used a second time. When an assembled mask is stored after use, 
the bottom opening of the canister should be closed with the plug 
stopper. 

Masks and canisters assembled and kept ready for use should be 
inspected and tested for leaks at periods of not more than tvo weeks. 
A man who is to wear a mask should also test it for fit and leaks be¬ 
fore he enters a dangerous place. To do this, the plug that closes 
the bottom opening is removed, the mask is put on, and adjustment 
made on the head bands until the mask fits closely but comfortably. 
Resistance to breathing should cause but little effort, nor should it be 
noticeably inconvenient. Then the bottom opening is closed with the 
palm of the hand and suction exerted with the lungs until the face 
piece collapses. If there are no leaks, the mask and canister will 
hold the vacuum for 15 seconds without change. If the mask is 
tight, the wearer should enter the gas cautiously to see that the canis¬ 
ter is active. Most gases and smokes may be perceived by their 
odor or by their irritating the nose or throat. When a canister is in 
use, failure at the end of its life is gradual, so that time is given for the 
wearer to escape. When evidences of failure are noticed, the wearer 
should immediately go to fresh air and replace the canister with a 
fresh one. 

HOW TO PUT ON A GAS MASK. 

The haversack or harness that supports a gas mask on a wearer is 
made adjustable to allow the canister to hang a comfortable distance 
from the face. After the adjustment is once made for a person it 
need not be changed. This arrangement of the haversack was called 
the 11 alert” position by soldiers, and they were trained to be able to 
remove a mask from the haversack and properly adjust it to the face 
in six seconds after command. Most uninformed persons in putting 
on a mask seem inclined first to put on the mask elastics like a hat 
and then adjust the face piece. This method is awkward, slow, and 
unsatisfactory. The rapid method taught to soldiers is this: Grasp 
the mask before the face with both hands, the thumbs pointing up¬ 
ward under the elastics, as shown in Plate VII, A, push the chin well 
into its position in the mask, then pull the elastics over the head as 
far as possible, as shown in Plate VII, B. After a little practice one 
is able to adjust in a single movement a Tissot type mask so that it is 
properly placed, gas-tight, comfortable, and the elastics are smooth. 


BUREAU OF MINES TECHNICAL PAPER 248 PLATE VII 




ADJUSTING GAS MASK^ B. ADJUSTING MASK WITH ONE MOVEMENT. 








TYPES OF BREATHING APPARATUS. 


27 


ABSORBENTS FOR GASES. 

The Bureau of Mines and the Chemical Warfare Service of the 
Army experimented with many absorbents for poisonous or toxic 
gases in general and with special absorbents for individual gases or 
classes of gases that might be used in warfare. The tests thus in¬ 
cluded most of the gases commonly met in the industries. 

The more useful absorbents are briefly described below: 

CHARCOAL. 

Charcoal, properly made, may be considered the one universal ab¬ 
sorbent for gases, as it absorbs to some degree every gas, both toxic 
and nontoxic. Its capacity and activit} 7 against any gas varies with 
the material from which it is made, but more especially, and over 
very vide limits, with the process of manufacture. However, char¬ 
coal has such a small capacity for absorbing certain gases met, both 
in warfare and in the industries, that it is of no practical value as an 
absorbent for them. Among these gases are carbon monoxide and 
ammonia. The properties of charcoal, as made by different proc¬ 
esses and from different materials, have been described by Lamb, 
Wilson, and Chaney, 28 and by Chaney. 29 It is sufficient to state here 
that the best charcoal, per unit of volume, is made from the dense 
shells of nuts, such as coeoanut, peach stones, and the like. Distilla¬ 
tion is done in ordinary coal-gas retorts at temperatures of about 
1,000° C. After distillation ends, the material is “activated” by 
passing steam or air through it at lower temperatures. Activation 
removes hydrocarbons from the cellular carbon surfaces, thus greatly 
increasing the activity and capacity of the charcoal. Charcoal made 
by ordinary processes of distillation is worthless as an absorbent in 
gas masks. Charcoal may be impregnated with other materials to 
increase its capacity for certain gases or to cause chemical decom¬ 
position of some gases. 

The special function of charcoal in the Army canister is to absorb 
organic vapors. Among the organic vapors that may be met in in¬ 
dustrial operations are: Acetone, alcohols, aniline, benzene, carbon 
bisulphide, carbon tetrachloride, chloroform, ether, formaldehyde, 
gasoline and petroleum distillates, toluene, and others. 

SODA-LIME. 

The properties and capacities of soda-limes made by different for¬ 
mulas are described in detail in the paper by Lamb, Wilson, and 


28 Lamb, A. B., Wilson, R. E., and Chaney, N. K., Gas-mask absorbents: Jour. Ind. Eng. Chem., vol. 
11, 1919, pp. 420-438. 

29 Chaney, N. K., The activation of carbon: Trans. Am. Electro-Chem. Soc., vol. 36, 1920, pp. 91-101 




28 


GAS MASKS FOR GASES MET IN FIGHTING FIRES. 


Chaney 30 previously cited. The standard Army soda-lime was made 
by mixing in the proportions indicated the ingredients named below: 


Composition of 

ingredients. Per cent. 

Hydrated lime. 45 

Portland cement. 14 

Infusorial earth. 6 

Sodium hydroxide. 1 

Water. Approx. 33 


The mixture was dried in slabs about 1 £ inches thick, crushed, and 
screened. The part that passed a screen of 8 meshes to the inch 
and remained on a screen of 14 meshes to the inch was used. Ma¬ 
terial this size was sprayed with a solution of sodium permanganate, 
after which the moisture content was about 13 per cent and the 
sodium permanganate content about 3 per cent. For certain indus¬ 
tries, such as require absorption of carbon dioxide, the amount of 
sodium hydroxide could be increased to advantage; also the per¬ 
manganate might be omitted and the formula otherwise varied. 

The especial function of soda-lime is to absorb acid gases. Some 
of the acid gases met in the industries are carbon dioxide, chlorine, 
formic acid, hydrogen chloride, hydrogen cyanide, hydrogen sulphide, 
nitrogen peroxide, phosgene, and sulphur dioxide. 

MIXED CHARCOAL AND SODA-LIME. 

The properties of the mixed charcoal and soda-lime, as used in the 
Army canisters, is the same for most gases as for each constituent 
when unmixed. But, for some gases, the mixture works to advantage. 
Thus phosgene is absorbed by both soda-lime and charcoal, but in 
the presence of moisture, which is always present, charcoal acts in a 
way to decompose phosgene and change it to carbon dioxide and 
hydrogen chloride gases. The capacity of charcoal for these gases 
is low and they are given off readily. However, the capacity of soda- 
lime for the liberated gases is higher than its capacity for phosgene. 
Thus the resultant capacity of the mixture for phosgene is higher 
than that due to each constituent acting separately. A similar action 
occurs with chlorine. 

AMMONIA ABSORBENTS. 

Perrott, Yablick, and Fieldner 31 investigated various materials 
for absorbing ammonia and found that the salt hydrates of certain 
heavy metals, such as copper, cobalt and nickel, and silica gel were 
very effective. The best material was copper sulphate or blue vitriol 
impregnated on granular pumice stone. This absorbent has a high 

50 Work cited, pp. 420-438. 

31 Perrott, G. St. J., Yablick, Max, and Fieldner, A. C., A new absorbent for ammonia respirators; Jour 
Ind. and Eng. Cbem., vol. 11,1919, p. 1013. 








TYPES OF BREATHING APPARATUS. 


29 


capacity for ammonia and will effectively remove the gas from air 
breathed in concentrations of the gas higher than the skin will bear. 
Thus it is man’s skin, rather than the gas mask worn, that limits his 
capacity to withstand ammonia gas in air. Although copper sul¬ 
phate is a most satisfactory absorbent for ammonia, it is useless 
against other gases. 

SILICA GEL. 

Silica gel 32 is a hornlike material, made by mixing together sodium 
silicate, also called water glass, and muriatic acid. It combines 
some of the useful properties of charcoal with that of an ammonia ab¬ 
sorbent. For certain organic vapors it has an absorption that com¬ 
pares favorably with high-grade charcoal. Its capacity and activity 
for ammonia are not equal to those of copper sulphate and pumice 
stone but are sufficient to make it a satisfactory absorbent for am¬ 
monia. This combination of the properties of both charcoal and 
kupramite (copper sulphate and pumice stone) in one material may 
make silica gel a very useful absorbent for some industrial purposes. 

ABSORBENT FOR CARBON MONOXIDE. 

Because of the widespread occurrence of carbon monoxide and 
its deadly nature, an adequate absorbent for it would be a great 
boon to fire fighters and to workers generally. The Bureau of 
Mines and the Chemical Warfare Service 33 have made progress in 
producing absorbents for removing carbon monoxide, and it is ex¬ 
pected that and these will soon be available for industrial use. 

GASES AND ATMOSPHERES AGAINST WHICH THE GAS MASK DOES 
NOT PROTECT. 

Absorbents for all gases for which absorbents are known have been 
described in the foregoing paragraph. Table 1 lists those gases and 
atmospheres against which no absorbent is known for protecting the 
wearer of a gas mask. 

In addition to noting the limitations of all gas masks, the reader 
should remember that canisters are now being produced commer¬ 
cially containing absorbents that may have a high capacity for a 
single gas or class of gases and not absorb others. For this reason, 
the purpose and capacity of the canister should be exactly under¬ 
stood by the wearer of a gas mask before he intrusts himself to it in 
a dangerous atmosphere. 

32 Patrick, W. A., Silica gel, U. S. Patent 1,297,724, Mar. 18, 1919. 

»3 Lamb, A. B., Bray, W. C., Frazer, J. C. W. The removal of carbon monoxide from air; Jour. Ind., 
and Eng. Chem., March, 1919, vol. 12, pp. 213-221. 

55299°—21-3 



30 


GAS MASKS FOE GASES MET IK FIGHTING FIRES. 
Table 1 .— Gases and atmospheres in which gas masks are inadequate . 


Gas or atmosphere. 


Where found. 


Remarks. 


Methane 


May be found wherever natural gas is 
produced or used; also in coal mines. 


Atmospheres deficient in 
oxygen. 


Flues, apparatus in industrial plants, 
mines and closed rooms in buildings 
after fires and explosions. 


Atmospheres containing 
higher concentrations 
of toxic gases. 


Chemical and metallurgical apparatus; 
rooms where large quantities of gas 
are evolved without adequate ven¬ 
tilation. 


Carbon monoxide 


Products of incomplete combustion of 
coal, wood, and most combustible 
matter; producer gas, blast-furnace 
gas and products of many chemical 
and metallurgical operations; coal 
gas, water gas, after-damp in mines 
after fires and explosions. 


No adequate absorbent is known. The 
gas is harmless in itself but may 
cause suffocation when present in 
air m sufficient quantity to reduce 
the oxygen content below 13 per 
cent. 

The wearer of a gas mask must have an 
adequate supply of oxygen in the 
atmosphere around him, regardless 
of the content of poisonous gas. For 
entering an atmosphere deficient in 
oxygen, either self-contained breath¬ 
ing apparatus or a helmet supplied 
with air from a pump through hose 
should be used. 

The gas mask is essentially an appa¬ 
ratus for removing from air toxic 
gases in comparatively low concen¬ 
trations, such as those on battle fields. 
In general, unless special in formation 
as to the activity and capacity of 
a mask is available, it should not be 
used in toxic gases having a concen¬ 
tration more than 1 or 2 per cent. 

No adequate absorbent is available at 
present; the Army mask canister is 
useless against this gas. Being 
odorless and tasteless, carbon mon¬ 
oxide may give no warning effects, 
and it is the most dangerous of all 
gases commonly met in civil life. 


EXPERIMENTS WITH INCOMPLETELY BURNING FIRES. 


In order to demonstrate the ineffectiveness of the Army canister 
in protecting against the products of incomplete combustion, two 
kinds of experiments were arranged. In the first experiment, a 
small, portable charcoal stove, such as is used by tinners for heating 
soldering irons, supplied the gases. Such charcoal fires produce no 
smoke, and the gases produced are invisible. In the second experi¬ 
ment, in a gas-tight unventilated chamber, built for experimental 
purposes, smoldering fires of excelsior, cotton waste, and like material 
produced gases and a thick dense smoke. 

EXPERIMENTS WITH CHARCOAL FIRES. 

Plate VIII shows the apparatus used for the experiments with a 
charcoal fire. Products of combustion were obtained from a point 
within the fire bed of a tinner’s stove. From the stove the gaseous 
products of combustion were drawn through a copper coil submerged 
in water for cooling. Air was then added, and the mixture was drawn 
through an Army gas-mask canister. From the canister the gases 
passed through a bell jar containing a perch on which sat a canary 
bird. Thence they passed through a flow meter, and finally were 
discharged from a suction pump. The glass parts of the line enabled 
an observer to see that the gas underwent no visible change. Carbon 
dioxide is the only gas other than carbon monoxide produced by the 
















TECHNICAL PAPER 248 PLATE VIII 


Tinner’s charcoal 
stove 


BUREAU OF MINES 


Flow meter for 
measuring 
flow of gas 


APPARATUS USED TO DEMONSTRATE THE INADEQUACY OF THE ARMY CANISTER 
FOR PROTECTION AGAINST CARBON MONOXIDE. 


















BUREAU OF MINES 


TECHNICAL PAPER 248 PLATE IX 



GAS CHAMBER USED FOR EXPERIMENTAL PURPOSES AT THE 
PITTSBURGH EXPERIMENT STATION OF THE BUREAU OF MINES. 






EXPERIMENTS WITH INCOMPLETELY BURNING FIRES. 31 


combustion of charcoal. This gas is absorbed by the Army canister, 
and its presence during the experiment described was indicated by 
the warming of the canister. The carbon monoxide overcame the 
canary, which fell from its perch in less than a minute. 

EXPERIMENTS WITH FIRES IN A CLOSED ROOM. 

In figure 3 are shown the details of the room or gas chamber used 
at the Pittsburgh experiment station of the Bureau of Mines. Plate 
IX is a picture of the chamber. The floor, walls, and ceiling are 
constructed entirely of sheet metal. The windows are of glass. 
The wooden doors, such as are made for large refrigerators, are 
lined on the inside with sheet metal, have edges bordered with rubber 
and handles made to exert a clamping effect and fasten the doors 
tightly against their jams. All metal joints are soldered. The glass 
windows are cemented in the metal sash with a putty containing 
linseed oil and red lead, so the joints between glass and metal are 
air-tight. Special valves are set in the roof for connecting the room 
with a flue leading to an exhaust fan. Each valve consists of a sheet- 
iron bell suspended in a tube of slightly larger diameter, which has 
at the bottom, inside, an annular space containing mercury. When 
the bell is seated in the annular space, the mercury seal makes the 
valve gas-tight. A chain attached to the bell runs over pulleys to 
a point where it may be reached by one on the outside of the chamber. 
Raising the bell into a closed space above a T in the pipe permits 
the gases in the chamber to be exhausted. 

Experiments have shown that the room is nearly gas-tight. 
During 24 hours the interchange of gas between the inside and out¬ 
side of the closed chamber amounts to less than 10 per cent of the 
chamber volume. 

Smoldering fires were built inside this chamber in the apparatus 
shown in figure 2 (p. 24). It consisted of an ash can with a large hole 
cut in one side near the bottom and set on bricks. Air could be blown 
through the can by means of an electric fan set before the hole. 
The combustible material was put into a holder made of two wire 
wastebaskets, and set inside the ash can. A spray nozzle held above 
the fire box was connected by hose to a faucet outside. Whenever 
a blaze burst out it was damped by a spray of water. 

It was necessary to keep the fire burning slowly to prevent a 
rapid liberation of heat, which would cause the walls to expand and 
endanger the glass windows^ A water-sealed inlet and outlet for 
air prevented excessive pressure from expansion of air in heating. 
Slow fires were desired, however, to simulate the actual fires that 
occur in closed rooms, cellars, and other confined places where the 
oxygen supply may be insufficient to support rapid and complete 


GAS MASKS FOR GASES MET IN FIGHTING FIRES 



ure 3—Detail of gas chamber used at the Pittsburgh experiment station of the Bureau of Mines for experimental purposes, a, Standard W. I. 2-inch pipe, threaded both 
ends set with two nuts and rubber gasket; b, 8-inch flange in roof for exhaust flue; c, 12-inch flange in roof for exhaust flue; d, motor; e, fan; /, refrigerator doors; g, 25-pound 
weight to submerge bell side in mercury well; h, annular mercury well; i, round-throated ferrule, finch hole; j, finch galvanized-metal sash cord; k, plate glass 36 by 44 inches; 

l, No. 16-gage sheet steel; m, ceiling; n, to hood; o, roof of gas house. 

Note.—N o. 24-gage steel roof; No. 16-gage steel floor. All sheet-metal joints soldered; back center panel has glass at top and bottom. 







































































































































































EXPERIMENTS WITH INCOMPLETELY BURNING FIRES. 


33 



Figure 4.—Army gas-mask canister, capacity 42 cubic inches of absorbent: a, Hose nipple; b r strong 
spring; c, stiff wire; d, toweling; e, mixed charcoal and soda lime absorbent; f, mixed charcoal and soda 
lime absorbent; g, cotton wool fillers between wire screens; h, rubber disk check-valve; i, wire-screen 
dome; j, sheet-metal stiffener for dome; k, air inlet. 

































































































































































































































































84 


GAS MASKS FOR GASES MET IK FIGHTING FIRES 


CARBON MONOXIDE, CARBON DIOXIDE, AND METHANE, PER CENT. 



’iNao aaa ‘NaoonxiN qnv nsoaxo 


TIME, HOURS 

Figure 5.— Curves showing relation between change of composition of gases in the experimental chamber, with time, during experimental fires. 















































































































































































































DISCUSSION OF RESULTS OF TESTS WITH FIRES. 35 

combustion and where there is greatest danger from carbon mon¬ 
oxide. Several fires with different combustibles were built in the 
apparatus. 

In order to test the protection from smoke afforded by Army gas 
masks in the different atmospheres, masks were worn into the 
chamber long enough at a time for the wearer to obtain the infor¬ 
mation but not long enough to be overcome by the carbon monoxide. 
In one test the effect was determined by subjecting a canary bird 
to the air from the chamber, which was first drawn through a canister. 
Comparative tests were also made with different kinds of respirators 
and gas masks. 

RESULTS OF TESTS WITH FIRES IN A CLOSED ROOM. 

The results of the tests with smoldering fires in the closed chamber 
are given in tabular form in Table 2, which follows. Figure 5 shows 
graphically the relation between change of composition of gas in the 
chamber with time for some of the experiments. Table 3 gives the 
results of tests on the different masks and respirators against smoke. 

DISCUSSION OF RESULTS OF TESTS WITH FIRES. 

Table 2 shows that smoldering fires form carbon monoxide in 
dangerous quantities. The proportion that may be present in any 
confined atmosphere where a fire exists depends upon duration of 
the fire, the volume of air present, and the rate of burning of the 
carbonaceous matter. Ventilation reduces the amount of poisonous 
gas by displacing some of the vitiated air with an equal volume of 
fresh air. Hence ventilation should be established in the space 
where the wearer of a gas mask has to go in order to reduce the 
danger of carbon monoxide poisoning. 

The irritating, suffocating smokes and gases produced by the 
fires were completely removed by the Airmy gas mask, but the 
wearer had no indication from the air he breathed that carbon 
monoxide was present. Although the mask was worn in the smoke 
for periods of three minutes or less, not long enough for a man to 
be overcome, the experiments with the canary birds show con¬ 
clusively that the danger existed. 

Closely confined spaces, like the one in the experimental chamber, 
are found in only a few places, as in mines and in cellars and vaults 
of buildings. Fires in such places are especially dangerous. In 
rooms of buildings above ground, there is usually enough ventila¬ 
tion to prevent accumulation of products of combustion in such 
concentration as may be encountered below ground. Also, the fire 
fighter may open doors and windows to insure an exit for the prod¬ 
ucts of combustion. 


36 


GAS MASKS FOR GASES MET IK FIGHTING FIRES. 


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Table 3. —Results of tests with different masks and respirators in smoke. 


DISCUSSION OF RESULTS OF TESTS WITp: FIRES. 


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38 


GAS MASKS FOR GASES MET IN FIGHTING FIRES. 


Table 3 shows that the respirators of the “pig snout” type offered 
no noticeable protection against smoke, whether the filtering medium 
was a moist sponge, paper, or a combination of fine silk gauze and dry 
sponge. The commercial canister with only one filter pad gave suf¬ 
ficient protection against smoke to be worn with full comfort. The 
odor of smoke that penetrated it was quite mild. The Army canisters, 
which contained two filter pads, gave complete protection against the 
smoke, and no odor of smoke could be detected. Although no smoke 
penetrated the Army masks in these tests, it has been found at times 
that a very small amount of smoke will pass through the Army masks. 
In those cases, the smoke particles have been unusually small. How¬ 
ever, the amount of smoke that has penetrated has not been sufficient 
to cause much discomfort. 

The experiments show especially that the Army gas mask may be 
used only to remove the suffocating and irritating smokes and gases 
of fires from the air breathed and that no reliance can be put upon it 
for protection from carbon monoxide. 

The length of time a fireman may safely remain in the smoky 
atmosphere will depend upon the amount of carbon monoxide present, 
and this the fireman can not possibly foretell. In the fire at the 
Pittsburgh Paper Stock Co., the firemen wearing masks worked for a 
total time of two to three hours without ill effects. On the other 
hand, firemen wearing masks have been overcome at Rochester, N. Y.,. 
and elsewhere, before they returned to fresh air. The building at 
Pittsburgh was well ventilated, but the fire at Rochester was in a 
basement, wdiere ventilation was poor. 

A man wearing a mask and breathing heavily at hard work in the 
atmosphere developed in experiment No. 3, Table 2, would probably 
be overcome in less than two minutes. Hence no definite limit of 
time that a man protected by a gas mask of the Army type may 
safely remain in a smoke-filled space can be set, but this conclusion 
may be made: When a fire fighter finds it necessary to enter a smoke- 
filled space inside a building, he may use the mask to protect himself 
from the smoke, but should accomplish his purpose and leave the 
dangerous region without delay. 

EXPERIMENTS WITH CARBON TETRACHLORIDE FIRE-EXTIN¬ 
GUISHER LIQUIDS. 

Chemists and many persons interested in fire fighting know that 
carbon tetrachloride, although a comparatively stable liquid, tends 
to decompose when heated to a high temperature. The decomposi¬ 
tion yields chlorine and other irrespirable gases. 

Because of the death of two men working in the Navy Department 
and the overcoming of an employee of the Bureau of Mines as a 



EXPERIMENTS WITH FIRE-EXTINGUISHER LIQUIDS. 39 

result of fighting fires with carbon tetrachloride extinguishers, the 
matter was investigated. The results showed that phosgene, hydro¬ 
gen chloride, and in some cases chlorine, as well as the vapors of 
carbon tetrachloride itself, were evolved. The mixture of these gases 
and vapors with the air in the chamber of 1,000 cubic feet capacity 
formed an atmosphere that would quickly kill a man unprotected 
against it. 

Commercial carbon tetrachloride and two well-known brands of 
carbon tetrachloride fire-extinguishing liquids were used in experi¬ 
ments. Qualitative tests for carbon bisulphide and chloroform gave 
the following results: 


Results of qualitative tests for carbon bisulphide and chloroform. 


Kind of liquid. 

Carbon bisulphide. 

Chloroform. 

Confmerdaiparb^Ti +.At.r»/>hioridP‘.... 

Present... 

Absent. 

Present. 

Do. 

'F.'srtinguisbf'r liquid Ua i __ 

_do. 

Extinguisher liquid No 2 , r T __ 

.do. 




Analytical distillation of the liquids gave the results shown in 
Table 4. 

Table 4. —Remits of distillation of carbon tetrachloride fire-extinguisher liquids. 


[200 ce. distilled in a 6-inch Hempel flask.] 


Amount distilled (per cent). 

Commercial carbon 
tetrachloride.— 
Barometer, 739 mm. 

Liquid No. 1.— 
Barometer, 730 mm. 

Liquid No. 2.— 
Barometer, 743 mm. 

Temp., 

°C. 

Sp.gr. 

Temp., 

°C. 

SP-fT- 
at 15 C. 

Temp., 

°C. 

Sp.gr* 

at 15 C. 

First drop .. 

67 


54 


54 


1 . 

71 


68 




2 . 

72 




70 



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1.599 

71 

1.567 

71.5 

1.564 


74.8 

1.596 

71.5 

1. o79 

72 

1.580 


75 

1.600 

72 

1.583 

73 

1.585 


75.1 

1.600 

72.5 

1.588 

73 

1.588 


75.3 

1.603 

73 

1.591 

73.5 

1.593 


75.3 

1.603 

73 

1.591 

74 

1.595 


75.4 

1.603 

73.7 

1.596 

74.5 

1.598 


75.5 

1.604 

74 

1.598 

75 

1.601 


75.5 

1. 606 

74.3 

1.601 

75.5 

1.602 


75.5 

1. 606 

74.5 

1. 603 

76 

1.603 

Dry point. 

75.5 


74.5 


76 



97.1 


97.5 


95 



1.3 


1.6 


4.5 

.897 








Remarks —First distillate of commercial carbon tetrachloride gave odor of carbon bisulphide. First 
distillate of liquid No. 1 smelled of chloroform. First distillate of liquid No. 2 smelled of carbon bisul¬ 
phide. Residue smelled of kerosene and was inflammable. 


From the results of Table 4 it appears that one of the commercial 
extinguisher liquids was carbon tetrachloride, with an admixture of 
chloroform to prevent freezing; the other was a mixture of carbon 































































40 GAS MASKS FOR GASES MET IN FIGHTING FIRES. 

tetrachloride, chloroform, and a high-boiling petroleum distillate, the 
last added for the same purpose. 

In order to determine the behavior of both commercial carbon 
tetrachloride and the other liquids as regards decomposition into 
gases when the liquids are put on a fire, experiments were made with 
small fires of excelsior and other inflammable material in the 1,000 
cubic foot chamber. Other experiments in which the extinguisher 
fluids were poured upon red-hot iron were made in the same chamber. 
The air was stirred with an electric fan to insure a uniform concen¬ 
tration of gas throughout the chamber. 

For investigating decomposition products obtained by pouring 
carbon tetrachloride on red-hot iron, a 6-inch channel iron was heated 
to bright red heat over a length of 2 feet; then it was quickly placed 
near the floor of the chamber, and the contents of a 1-quart fire 
extinguisher were steadily sprayed or poured upon it by a man 
wearing a gas mask or one-half hour breathing apparatus. After the 
extinguisher was emptied, the fan was started, and samples of the 
gas were taken as soon as its concentration was uniform. These 
samples were analyzed for various products of decomposition, in¬ 
cluding carbon tetrachloride (CC1 4 ), muriatic acid gas (HC1), phosgene 
(COCl 2 ), and chlorine (Cl 2 ) in parts per million (p. p. m.); and carbon 
monoxide (CO), carbon dioxide (C0 2 ), oxygen (0 2 ), and nitrogen 
(N 2 ), in per cents. 

Similar experiments were made with burning excelsior, rags, and 
other waste material. The results of these experiments are given in 
Table 5. 

Table 5 shows that in all the experiments the atmosphere created 
by using the fire extinguisher was exceedingly dangerous. A rather 
surprising result of this investigation was the fact that phosgene,which 
is extremely poisonous, was liberated in every experiment in toxic 
quantities. 

Experiment No. 1, in which 800 c. c. of carbon tetrachloride wa& 
poured on a red-hot 4-inch I beam, showed 168 parts per million of 
phosgene in the atmosphere of the chamber. This concentration i& 
fatal. Chlorine was not found as a decomposition product in most of 
the experiments. Experiments Nos. 2 and 6 show some chlorine, 
but not enough to be considered very dangerous. 

Small quantities of carbon monoxide were given off in most of the 
experiments, both with liquid No. 1 and liquid No. 2. Hydrogen 
chloride or muriatic acid gas was present in sufficient concentration 
to be irritating, but would hardly be dangerous. Carbon tetrachloride 
vapor was present in concentrations ranging from 0.2 to 0.6 per cent, 
or 2,000 to 6,000 parts per million. This concentration is not con¬ 
sidered sufficient to produce anaesthesia in a short time. However, 
if the chamber volume were much smaller there would undoubtedly 


Table 5. —Results of experiments with heated carbon tetrachloride fire-extinguisher liquids in the closed chamber. 


EXPERIMENTS WITH FIRE-EXTINGUISHER LIQUIDS, 


41 













































42 


GAS MASKS FOR GASES MET IK FIGHTING FIRES. 


be a high enough concentration of carbon tetrachloride vapor to cause 
anaesthesia by itself, and men would become instantly unconscious, 
and furthermore the phosgene present would produce effects in the 
lungs and respiratory system that would prove fatal. 

When commercial carbon tetrachloride is poured on red-hot iron, 
it produces a yellowish smoke that looks much as though chlorine 
were one of the decomposition products. This is not the case, how¬ 
ever, and no chlorine was found, either by chemical test or by odor, 
except in experiments 2 and 6. 

The predominating odor was carbon tetrachloride itself, phosgene, 
and hydrochloric acid. The yellowish color of the smoke was found 
to be due to iron chloride formed by the action of carbon tetrachloride 
on the hot iron. This iron chloride vaporizes, then reacts with the 
moisture in the air, hydrolizes, and forms hydrochloric acid and iron 
oxide. Liquid No. 1 gives the same sort of smoke as does com¬ 
mercial carbon tetrachloride, whereas liquid No. 2 gives a black smoke, 
its color seemingly due to particles of carbon formed by decomposi¬ 
tion of the kerosene or other petroleum oil that is put in this extin¬ 
guisher to lower the freezing point. 

It was of‘course impossible for a man to take even one breath of the 
atmosphere created in the gas chamber while spraying the extin¬ 
guisher on hot iron or burning excelsior. 

DISCUSSION OF RESULTS OF TESTS WITH LIQUIDS CONTAINING CARBON 
TETRACHLORIDE. 

All three liquids decomposed in the same way when put on a fire. 
Whether the source of heat was a wood fire or red-hot iron made no 
material difference, except that with the fires the percentage of carbon 
monoxide and perhaps of certain other gases was largely increased, 
owing to products of decomposition from the combustible itself. 

As a result of these experiments, the Bureau of Mines believes that 
carbon tetrachloride extinguishers should not be used on fires in con¬ 
fined spaces by persons who are not protected against the fumes pro¬ 
duced in this wav, or who are unable to hold their breath and get 
away at once from the immediate vicinity of the fire after applying 
the extinguisher. The Army gas mask will provide adequate protec¬ 
tion from all the gases, except carbon monoxide, which was not found 
in sufficient concentration to be dangerous in the short time required 
to use an extinguisher. The results of the tests should not discourage 
the use of carbon tetrachloride fire extinguishers, which are very 
effective in extinguishing incipient fires, because in nearly every fire 
the ventilation, or the large amount of air usually present, prevents 
the formation of very dangerous concentrations of poisonous gas. 
Also the operator is nearly always able to escape easily and quickly 
from the vicinity of the gas as soon as he notices it. The purpose of 


EXPERIMENTS WITH FIRE-EXTINGUISHER LIQUIDS. 


43 


the tests made by the bureau was to show the danger of using such 
extinguishers in small, unventilated places where rapid escape is 
impossible. 

ATMOSPHERES IN BURNING MINES. 

Although no analyses of vitiated air from burning buildings are 
available, so far as is known, the Bureau of Mines has made many 
analyses of gases in burning mines. Some representative analyses 
are given in Table 6. 

These figures show conclusively the presence of carbon monoxide in 
deadly amounts and prove that the ordinary Army gas mask can not 
protect the wearer from poisonous gases in a burning mine. The 
Army type of gas maslc is not to be used in burning mines. 

As a result of the experience of its engineers and of the collection 
of such data as are given in Table 6, the Bureau of Mines recommends 
the use of self-contained oxygen-breathing apparatus by men doing 
rescue work in mines. If such apparatus are not available, it is 
preferable to enter the mine without breathing apparatus rather 
than to trust to other types of breathing appliances. The Army 
gas mask would give the wearer in the mine a false sense of security 
by removing distasteful fumes from the air breathed and allowing 
the carbon monoxide to pass through unnoticed. The smoke and 
gases from fires in mines serve to warn the workers of the presence of 
dangerous gas. 

The Bureau of Mines has published considerable information on 
mine fires and the use of oxygen-breathing apparatus. Among its 
publications are Bulletins 44 and 62; Technical Papers 11, 13, 24, 
59, 62, 82, 103, 134, and 150; Miners’ Circular 10; and a hand¬ 
book on rescue and recovery work in mines. The titles of these 
publications are given in the list on page 67. 

UTILITY OF ARMY GAS MASKS IN FIGHTING FIRES. 

Whether or not firemen should adopt the Army gas mask for 
general use has been much discussed. Theoretically it would seem 
that the half-hour oxygen-breathing apparatus, which keeps out all 
gases and supplies oxygen, would be much safer than the gas mask 
for fire fighting. But practical experience shows that firemen, as a 
rule, do not favor oxygen-breathing apparatus. To them it seems 
cumbersome and uncertain in action. The combination of oxygen 
cylinder, breathing bag, regenerator canister, valve and pressure 
gage appears too complicated for the rough and ready work of fire 
fighting. Although such apparatus has been on the market for a 
number of years, it is seldom put into practical use, even when on 
hand, at fires. Firemen prefer to take their chances unencumbered, 
or at most simply to tie a wet handkerchief or towel over the nose 
and mouth to keep out some of the smoke. 


Table 6. —Analyses of gases from mine fires. 


44 


GAS MASKS FOR GASES MET IK FIGHTING FIRES.. 


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EXPERIMENTS WITH FIRE-EXTINGUISHER LIQUIDS. 


45 


Therefore the utility of the gas mask must be considered from the 
practical point of view rather than the theoretical. A review of the 
many reports of tests in experimental fires by city fire departments 
shows: (1) That firemen are favorably impressed with the simplicity 
of the gas mask and will wear it; (2) that in the great majority of 
these tests it protected the eyes and throat from irritating smoke 
and was a great improvement on sponge respirators and wet cloths; 
(3) that the mask did not encumber the wearer or retard his effective¬ 
ness in fire fighting; (4) that no special training was required in 
learning how to use the mask; (5) that in comparison with the oxygen¬ 
breathing apparatus very little attention is required to keep the gas 
masks in good condition. 

These experiments by fire departments corroborate the experiments 
of the Chemical Warfare Service and of the Bureau of Mines in 
proving conclusively that the Army gas mask, when fitted with a 
canister containing cotton filter pads, activated charcoal, and soda 
lime, effectively filters out irritating smoke particles, and, in addition, 
protects against most chemical fumes in the concentrations likely to 
be met in fires. 

However, in using the Army mask the following serious limitations 
must be kept in mind: (1) It furnishes no oxygen; hence it should 
not be worn into a place where a safety lamp or a fireman’s oil-burn¬ 
ing lantern will not burn; (2) it should not be used where there is 
reason to suspect carbon monoxide, as in smoldering fires in base¬ 
ments and other confined, unventilated spaces, and especially in con¬ 
fined places where broken illuminating gas pipes add carbon monoxide 
to the air; (3) it offers very poor protection against ammonia; (4) 
finally, the Army mask may break down in unusually high concentra¬ 
tions of poisonous gases. It was originally designed for outdoor 
use, where the poisonous gases are considerably diluted with air. 
Caution must be used, therefore, in going into rooms where the con¬ 
centration of the accumulated gas may be great enough to pass 
through the mask. 

RECOMMENDED GAS MASK FOR FIRE FIGHTERS. 

Perhaps the most serious limitation of the Army mask for fire 
fighting is its inability to protect against ammonia and carbon 
monoxide. Although special ammonia canisters are now available 
commercially, and carbon monoxide canisters soon will be available, 
the fire fighter does not know in advance what gas or combination of 
gases he may find. Many buildings contain ammonia refrigerating 
plants, and all cities outside the natural gas belt are piped for arti¬ 
ficial gas containing carbon monoxide. The fireman, therefore, must 
have, in a single mask, protection against all these gases, either by 
attaching several canisters to the same face piece or by increasing 
55299°—21- 1 



46 


GAS MASKS FOR GASES MET IN FIGHTING FIRES. 


the size of the fireman’s canister to about three times the volume of 
the present Army canister. This larger canister should contain 
special absorbents for ammonia and carbon monoxide, when the 
latter is developed, in addition to the present filling of charcoal, 
soda lime, and filter pads. With such a canister, a fireman could 
safely entler any atmosphere in which a safety lamp would burn. 

SPECIFICATIONS FOR FIRE-FIGHTERS’ GAS MASK. 

In order to promote the production of an adequate combination 
gas mask for fire fighters, the Bureau of Mines will cooperate with 
city fire departments in obtaining more accurate information as to 
the actual gases present in connection with fires, and with manufac¬ 
turers of gas masks in testing and approving suitable gas masks when 
submitted to the bureau in accordance with schedule 14. 34 

Fire departments desiring to cooperate in obtaining information on 
the presence of carbon monoxide in gases from fires should com¬ 
municate with the Pittsburgh experiment station of the Bureau of 
Mines. They will be furnished vacuum bottles, with full instructions 
for taking samples and forwarding them to the bureau’s laboratory 
for analysis. 

Gas masks submitted by manufacturers for approval will be tested 
to determine whether they pass the following requirements: 

REQUIREMENTS FOR BUREAU OF MINES APPROVAL . 35 

I. COLOR AND MARKINGS. 

Distinctive color and marking to indicate the purpose of each canister or absorbent 
container are required for the purpose of safeguarding the wearers. The colors required 
are indicated in the following table: 


Table 7. —Colors to indicate purpose of masks. 


Mask type letter. 

Chemical properties of gases absorbed. 

Distinctive color required. 


Acid.*. 

White. 

Black. 

Green. 

Color to be assigned. 

White or black stripes. 

Yellow. 

Combinations of those above. When 
a dust filter is combined with a gas 
respirator it is to be indicated by 
black or white stripes. 

33 

Organic vapor. 

Q 

Ammonia. 

D. 

E 

Other special individual gases. 

Dusts, smokes, mists.. 

AB. 

Combinations of those 
above. 

Acid and organic vapors. 

Combinations of those above. 


The canisters or containers for the absorbent material shall be either painted com¬ 
pletely in these colors or the color shall be made a distinctive part of the canister 
design. On the canister shall be indicated, in bold letters, this statement: 

FOR USE ONLY IN.. (Name gas or gases.) 


M Procedure for establishing a list of permissible gas masks; fees, character of tests, and conditions under 
which gas masks will be tested. Sched. 14, Bureau of Mines, 1919. 

35 Procedure for establishing a list of permissible gas masks; fees, character of tests, and conditions under 
which gas masks will be tested. Sched. 14, Bureau of Mines, 1919. Supplement to Sched. 14, Bureau of 
Mines, 1920. 
























UTILITY OF ARMY GAS MASKS IK FIGHTING FIRES. 


47 


The manufacturer will state the gas or gases, or classes of gases, in which the gas mask 
is to be used. For this purpose, it is permissible to attach a metal plate bearing the 
proper inscription in raised or other distinct letters, or to stamp the statement into the 
metal of the can with a male and female die. The statement may be printed or 
stenciled with paint, or paper labels may be used. The latter must be attached with 
a heat-proof cement and varnished to prevent loosening by moisture. 

If a dust respirator is combined with gas absorbents, the fact should be indicated, as, 
for example: 

FOR USE ONLY IN.AND IN DUSTS. (Name gas or gases.) 

The knapsack or case in which the gas mask is kept must also have the same state¬ 
ment indicated conspicuously in bold letters. The distinctive color or colors may be 
that of the letters themselves or that of the background, or part of the design, in such 
fashion that the distinctive colors are prominent. 

Metal plates or painted or printed stencils may be used on the knapsacks, but 
paper labels will not be permissible here. 

For chemical smokes or fumes, the canister or container for the absorbent material 
shall be of a color to indicate the purpose of absorbent material contained, and shall 
be striped with a strongly contrasting color, either black or white, to indicate the 
filters. The stripes may be so placed as to indicate the number and position of the 
filters. On the canister or container shall be indicated, in bold letters of contrasting 
color, this statement: 

FOR USE ONLY IN-. (Name gas or gases and chemical fume, 

according to the purpose of the manufacturer.) 

The knapsack or case in which the gas mask is kept must also have the same state¬ 
ment indicated on front and back, in bold letters on a striped background of the 
proper colors, to indicate the purpose of the absorbent and the filter. 

2. MATERIALS. 

The gas mask and equipment must be constructed of materials in all its 
parts suitable for the purpose they must serve. This applies to the fabric, rubber, 
metal, chemical, and other parts. 

3. DESIGN AND CONSTRUCTION. 

The excellence of design and mechanical construction, as well as the workmanship, 
will be considered. This will be done with regard to safety to the wearer, freedom 
of his movements and his vision, the fit of the face and head pieces, and the comfort 
which is afforded under all conditions of use. There will also be considered the 
ease with which canister or other parts of necessarily short life may be replaced by 
fresh parts, and the tightness of the whole apparatus, with a view to insuring the 
wearer against leaks of unpurified air, both before and after such changes are made. 

4. FACE-PIECE TEST. 

Two men wearing the gas masks will enter a room containing 1 per cent of sulphur 
dioxide; if necessary, a canister for acid gases will be attached to the mask for this 
test. Thirty minutes will be spent in work designed to provide observations on the 
freedom of movement permitted, freedom from leaks, and the comfort allowed to 
the wearer. The time will be divided as follows: 

10 minutes: Walking, turning head, dipping chin. 

5 minutes: Calisthenic movements, such as swinging arms, turning body, bending 
body at hips. 

10 minutes: Sitting at rest, then walking and easy movements. 




48 


GAS MASKS FOR GASES MET IN FIGHTING FIRES. 


5 minutes: Pumping air into gas cylinder of about 1 cubic foot capacity, with a tire 
pump, to a pressure of 25 pounds. 

To meet approval, it will be necessary that no sulphur dioxide come through the 
mask during the test and that no undue discomfort be experienced because of the fit 
or other mechanical features of the gas mask. 

5. RESISTANCE TO FLOW OF AIR. 

Before and after the chemical tests described under paragraphs Nos. 6 and 7, the 
pressure drop of air passing through the canisters at a rate of 85 liters per minute will 
be determined in inches of water-column height. At no time must the resistance 
exceed 4 inches of water. 

The resistance to flow of air of the complete mask and canister to inspiration and 
to expiration, will be determined on a mechanical apparatus, the rate being 85 liters 
per minute continuous flow; the resistance must not exceed 6 inches of water pressure. 

6. CANISTER TESTS. 

Type A—Acid gases .—Nine canisters or parts containing the absorbent, separated 
from the face piece and harness, will be tested on a chemical testing apparatus, under 
these conditions: 

(1) Number of canisters, three. 

Gas used for testing, chlorine. 

Concentration of chlorine in air, 5,000 parts per million. 

Humidity, 50 per cent relative humidity. 

Temperature, room temperature (approximately 25° C.). 

Rate of flow of gas, 32 liters per minute, continuous flow. 

(2) Number of canisters, three. 

Gas used for testing, hydrogen cyanide. 

Concentration of hydrogen cyanide in air, 5,000 parts per million. 

Humidity, 50 per cent relative humidity. 

Temperature, room temperature (approximately 25° C.). 

Rate of flow of gas, 32 liters per minute, continuous flow. 

(3) Number of canisters, three. 

Gas used in testing, sulphur dioxide. 

Concentration of sulphur dioxide in air, 5,000 parts per million. 

Humidity, 50 per cent relative humidity. 

Temperature, room temperature (approximately 25° C.). 

Rate of flow of gas, 32 liters per minute, continuous flow. 

Tested in this way, the life or service time must be at least 20 minutes for each 
canister. The end of the life will be at the time at which a test shows 5 parts per 
million of chlorine, hydrogen cyanide, or sulphur dioxide in the air coming from 
the canisters. 

Type B—Organic vapors .—Three canisters or parts containing absorbent, separated 
from the face pieces and harness, will be tested on a chemical apparatus, under these 
' conditions: 

Vapor used for testing, carbon tetrachloride. 

Concentration of carbon tetrachloride in air, 5,000 parts per million. 

Humidity, 50 per cent relative humidity. 

Temperature, room temperature (approximately 25° C.). 

Rate of flow of gas, 32 liters per minute, continuous flow. 

Tested in this way, the life or service time of each canister must be at least 20 
minutes. The end of the life will be the time at which the air, after passing through 
the canister, imparts a green color to a small gas flame containing some of the air 
admixed with the gas and impinging on a clean copper wire. 


SPECIFICATIONS FOR FIRE-FIGHTERS 1 GAS MASK. 


49 


Type C —Ammonia. —Three canisters containing the absorbent, separated from the 
face pieces and harness, will be tested on a chemical testing apparatus, under these 
conditions: 

Concentration of ammonia in air, 20,000 parts per million, or 2 per cent by volume. 

Humidity, 50 per cent relative humidity. 

Temperature, room temperature (approximately 25° C.). 

Rate of flow of gas, 32 liters per minute, continuous flow. 

Tested in this way, the life or service time must be at least 20 minutes. The end of 
the life will be the time at which the air, after passing through the canister, contains 
100 parts per million, or 0.01 per cent by volume, of ammonia. 

Type D — Other special individual gases. —Similar tests will be performed on other 
special gases, and will be arranged as the need arises. 

Type E — Smoke, dust, and mist filters—Class I. —Three filters, separated from the 
face piece and harness, will be tested on a smoke-testing apparatus, under these 
conditions: 

Fume used, tobacco smoke. 

Rate of flow of gas, 85 liters per minute. 

Length of test, five minutes. 

Tested in this way, the filters must retain at least 95 per cent of the passing tobacco 
smoke at the end of the five-minute period. 

Class II. —Six filters, separated from the face piece and harness, will be tested on a 
smoke-testing apparatus and by man tests as follows: 

(a) Tobacco-smoke test. 

Number of canisters, two. 

Rate of flow of gas, 85 liters per minute. 

Length of test, five minutes. 

Tested in this way, the filters must retain at least 50 per cent of the passing tobacco 
smoke at the end of the five-minute period. 

( b ) Cotton-smoke man test. 

Number of canisters tested, two. 

Nature of test: Two men will wear the masks into a room of about 1,000 cubic feet 
capacity filled with the smoke from the smudge burning of 1 pound of cotton waste. 
If the masks are not made with attached canisters for the absorption of gases, such 
canisters shall have been attached to the filters. The men will remain 10 minutes in 
the room if the canisters fulfill the following requirement: No discomforting irritation 
of the respiratory system or eyes to be experienced by either man; this requirement 
is necessary for approval. 

(c) Tin tetrachloride man test. 

Number of canisters, two. 

Nature of test: Two men stationed outside of a chamber of about 1,000 cubic feet 
capacity, in which is an atmosphere containing 500 parts per million as by volume of 
tin tetrachloride fumes, will breathe the atmosphere from the chamber through the 
canisters or filters. If necessary, a canister for absorbing acid gases will be attached 
to the filters. The men will continue the test for 20 minutes if the filters fulfill the 
following requirement: No discomforting irritation to be experienced by either man; 
this requirement is necessary for approval. 

The applicant will state the class for which he desires tests. 

Other types. —Combinations for different types of gases, as above: Canisters may be 
tested according to two or more methods, under (A), (B), (C), (D), and (E) above, to 
secure approval for different gases classed under the different types. 

To meet the approval of the Bureau of Mines, it will be necessary that the life for 
gases in each class or type be equal to the separate requirements. 


50 


GAS MASKS FOE GASES MET IK FIGHTIKG FIRES. 


7. CHEMICAL STABILITY. 

To determine the chemical stability under extreme conditions of dryness and 
moisture, two canisters will be subjected to each of the following tests for which 
approval is desired: 

(а) Air free from carbon dioxide, at room temperature and 25 per cent relative 
humidity, will be passed through each canister, at a rate of 64 liters per minute, for a 
period totaling six hours. The canisters will then be tested, as described under para¬ 
graph 4, against gases as follows: 

Approval for acid gas, chlorine. 

Approval for organic vapor, carbon tetrachloride. 

Approval for ammonia, ammonia. 

Approval for special gas, special gas to be arranged. 

Approval for dust and mists, no test. 

Approval for combinations, any two or more of above. 

To meet approval, the lives must not fall below 10 minutes in any test. 

(б) Air free of carbon dioxide, at room temperature and 85 per cent relative humidity, 
will be passed through each of two canisters at a rate of 64 liters per minute, for a 
period totaling six hours, and the canisters will then be tested as described in (a) above. 

To meet approval, the lives must not fall below 10 minutes in any test. 

8. HIGH RATES OF BREATHES G AND MAXIMUM CONCENTRATION. 

To insure protection at high rates of breathing in gas of high concentration, a stream 
of air containing 1 per cent of gas and flowing at a rate of 64 liters per minute will be 
passed continuously through a canister. The other conditions of the tests will be 
these: 

Humidity, 50 per cent relative humidity. 

Temperature, room temperature (approximately 25° C.). 

Gas used in testing: 

Approval for acid gas, phosgene. 

Approval for organic vapors, carbon tetrachloride. 

Approval for special gas. ammonia, or other special gas. 

Approval for dusts and mists, no test. 

Approval for combinations, any two or more of the above. 

Concentration, 10,000 parts per million, or 1 per cent by volume, for any gas. 

Number of canisters, two, tested against any gas. 

To meet the approval of the Bureau of Mines, the life of the canisters under any of 
the above tests against gas must be at least five minutes. 

APPROVAL FOR HIGHER CONCENTRATIONS. 

The Bureau of Mines requires that a gas mask pass the tests outlined above in order 
to secure approval for use in concentrations of 1 per cent of gas, which is the minimum 
for which the bureau will grant approvals. To secure the approval for higher con¬ 
centrations, the canister must pass tests similar in every way, except that the concen¬ 
tration is increased in test 8 above in steps of 1 per cent, as far as practicable, and those 
tests are made on each gas for which approval in higher concentrations than 1 per cent 
is desired. Approval will be granted for use of the gas mask in the maximum concen¬ 
tration for which it successfully passes the test. 


SUMMARY AND CONCLUSIONS. 


1. City firemen have been overcome while wearing Army gas 
masks for fighting fires. This paper gives information on the use 
and limitations of gas masks and breathing apparatus in general. 

2. The chemistry of combustion and of the various gases found in 
fires and commonly met in industrial plants are described. 

3. The effects of poisonous gases when breathed and the methods 
of treatment for gas poisoning are discussed. 

4. Self contained oxygen breathing apparatus gives protection against 
all gases and atmospheres to fire fighters in mines and buildings. 

5. Because of their weight, time required for adjustment, and care 
necessary to keep them in working condition, self-contained oxygen 
breathing apparatus have not been considered entirely satisfactory, 
especially by city firemen. 

6. The Army gas mask often fills the need of a smoke and chemical 
fume filter, but will not protect against carbon monoxide, atmospheres 
deficient in oxygen, or atmospheres containi n g a mm onia gas. 

7. The Army gas mask gives excellent protection against smoke 
and the irritating and distasteful products of combustion. 

8. Special absorbents have been developed for removing ammonia 
gas from air breathed, which protect the wearer in concentrations as 
high as the skin will bear. 

9. Poisonous carbon monoxide is given off from smoldering fires in 
poorly ventilated places, such as cellars, vaults, and small closed 
rooms. The use of ordinary gas masks in such places is dangerous. 
Also, where the same gas may come from broken illuminating gas 
pipes, their use is dangerous for the same reason and because of the 
possibility of insufficient oxygen. 

10. There is little danger from carbon monoxide from open, freely 
burning fires. 

11. Gas masks of the Army type should not he used in mines after 
fires and explosions. Self-contained oxygen breathing apparatus 

should be used. .... 

12. Carbon tetrachloride fire-extinguisher liquids when used on fires 
in confined spaces produce small quantities of the poisonous gases, 
phosgene, chlorine (in some cases). and hydrogen chloride, as well as the 
vapors of carbon tetrachloride itself. These gases are dangerous. The 
Army type gas mask is recommended for protection against them. 

13" The Bureau of Mines will cooperate with fire departments in 
determining the nature of gases found in fires and with manufac¬ 
turers in approving suitable gas masks for fire fighting. 

14. Enough progress has been made by chemists wor king under 
the direction of the Bureau of Mines and subsequently in the Chem¬ 
ical Warfare Service, in the development of an absorbent for carbon 
monoxide to raise the hope that a combination canister for a fireman’s 
mask, which will protect against smoke, ammonia, carbon monoxide, 
and practically all chemical fumes, will soon be commercially avail¬ 
able. When this is accomplished, a fireman can be protected m any 
atmosphere where a safety lamp will burn. 


Table 8. — Conversion table for gases: Parts per million versus milligrams per liter. 

[25° C. and 760 mm. mercury, barometric pressure.] 



GAS MASKS FOR GASES MET IN FIGHTING FIRES 


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weight. 

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1 p. p.m.- 
Mg./L. 

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1 p. p. m.- 
Mg./L. 

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.0001227 
.0001636 
.0002045 
.0002454 
.0002863 
.000327 
.000368 
.000409 
. 000450 
. 000491 
.000532 
.000573 
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.000736 
.000777 
. 000818 
.000859 
. 000900 
. 000941 
. 000982 
. 001022 
.001063 
.001104 
.001145 
. 001186 
. 001227 
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. 001391 
. 001432 
. 001472 
. 001513 
. 001554 
. 001595 

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SUMMARY AND CONCLUSIONS 


53 


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APPENDIX. 


CONVERSION TABLE FOR GASES—PARTS PER MILLION VERSUS 
MILLIGRAMS PER LITER. 


The concentrations of very dilute gaseous impurities in air are conveniently 
expressed in parts by volume of the gas in question, considered as a perfect gas, per 
million parts of air-gas mixture. The symbol for parts per million is p. p. m. For 
toxicological and chemical purposes the weight of the gaseous impurity per unit 
volume of the mixture is frequently desired; milligrams of the gas in question per 
liter of mixture, considered as a perfect gas and measured at the average room condi¬ 
tions of 25° C. and 760 mm . of mercury barometric pressure, is customarily used to 
express this. Mg./L. is used as the symbol. The conversion table that follows has 
been compiled to aid in converting the expressions of gases in parts per million to 
milligrams per liter and vice versa. It will prove helpful to chemists and toxicologists. 

The compilation has been based on the following reasoning: 

On a physical-chemical basis a weight in grams of any pure gas or vapor numerically 
equal to its molecular weight has been assumed to produce 24.45 liters of a perfect gas 
when measured at 25° C. and 760 mm. of mercury barometric pressure. 

Then, if a: is the molecular weight of the gas, x grams will occupy a volume of 24.45 
liters at the stated conditions, which will be considered constant hereafter. 

(1) x grams=1,000# milligrams. 

(2) And 1,000a; milligrams O 24.45 liters of the gas. 

. . 24.45 liters 24.45 ,. ,. , 

(3) 1 milligram O —^qqq^— =C= cubic centimeters. 

24.45 

(4) 1 milligram in 1 liter of total gaseous mixture O c. c. in 1,000 c. c. total. 


94 45 

(5) And, —^ c. c. in 1,000 c. c. 


1,000X24.45 

x 


in 1,000,000 c. c. total. 


(6) Therefore, 1 milligram per liter O - c * c * i- n 1,000,000 c. c. total. 

24 450 

(7) Simplifying, 1 mg. per liter = ' x — c. c. per 1,000,000 c. c. 


24 450 

(8) Or 1 Mg./L. = : —^ p. p. m. 

Transformation of equation (8) gives— 

(9) 1 p. p. m,= 24 7 450 

The values in the conversion table have been calculated from equations (8) and (9) 
for molecular weights from 1 to 300. The accuracy throughout is 1 part in 250 parts. 
Examples will show how the tables are used: 

Given a concentration of chlorine of 5 Mg./L., what is the concentration by volume? 
Chlorine has a molecular weight of 70.92, or 71 in round numbers. The conversion 
table shows that for a molecular weight of 71— 

(10) 1 Mg./L.=344 p. p. m. 

(11) Therefore, 5 Mg./L. of chlorine=5X344=l,720 p. p. m. 

Given a concentration of ammonia in air of 2 per cent by volume, what is the weight 
per liter at 25° C. and 760 mm. of mercury barometric pressure? 

Ammonia has a molecular weight of 17. Then, from the table after molecular 

weight 17— 

(1.2) 1 p. p. m. =0.000695 Mg./L. 

(13) 2 per cent by volume=20,000 p. p. m. 

(14) 20,000 p. p. m. of ammonia=20,000X *000695=13.9 Mg./L. 


55 










56 


GAS MASKS FOR GASES MET IK FIGHTING FIRES. 


POISONOUS DOSES OF INDUSTRIAL GASES AND VAPORS IN AIR. 

The following table of poisonous doses of industrial gases and vapors when mixed 
with air summarizes partly the results of many investigators who have studied the 
effect of polluted air on man and animals. It has been difficult to arrange the data 
into a homogeneous table, because the standards of measurement and methods of 
investigation have not been uniform. In order to arrive at the arrangement given 
here, the authors have taken some liberties in transposing and interpreting many of 
the data. For this reason reference to original sources, which are cited in all cases, 
should be made for exact statements. 


Table 9. — Poisonous doses oj industrial gases and vapors in air. 





Least amount required to cause irritation. 






Noxiousness, impossible to 
breathe several minutes. 

Toxicity or lethal dose. 




Least detectable odor. 

Eyes. 

Throat. 

Coughing. 


inhaled for l hour without 
serious disturbances. 

hour. 

Mice, 10 minutes, exposure. 

Dogs, 30 minutes, 
exposure. 

Cats, 30 minutes, 
exposure. 

Man, 30 minutes, exposure 

Kill most animals in very short 
time. 

Relative 

toxicity, 

CCL=1. 

Physiological action of gas. 

Name of gas. 

Mg./L. 

P. p. m. 

Mg./L. 

P. p. m. 

Mg./L. 

P.p. m. 

Mg./L. 

P. p. m. 

Mg./L. 

P. p. m. 

Mg./L. 

P.p.m. 

Mg./L. 

P. p. m. 

Mg./L. 

r.p.m. 

Mg./L. 

P. p. m. 

Mg./L. 

P. p. m. 

Mg./L. 

P. p. m. 

Mg./L. 

P. p. m. 

Mg./L. 

P. p. m. 




















1 49.0 

120,600 











Acetone. 

Alcohol. 

Ammonia. , 

Anilin 


























8 0.01 

Asphyxiant. 

10.037 

153.0 

> 0.485 

i 698.0 

‘ 0.284 

i 408 

» 1.20 

1 1,720 

2 0.070 

2 100 

*7-26 

*0.21 

2 0.4-0.6 

2 300 

2 1.74-3.13 

"v2*500^4,566’ 













Respiratory irritant—lachrv-uator; 
acts on tissue. 

Asphyxiant;combines with blood... 















*1*2.5" 

.1 338 










Arsenic trichloride. 

Arsine. 

Benzene. 

Bromine. 

















'>6.33' 

.1*103* 




4 2>0 




WSJStf* blood. 









2 5-10 

2 1,570-3,130 

*10-15 

2 3,130-4,700 





>1 61 

>119,000 








Asphyxiant. 












•4 

2 6.026-6.039 

.V 40^66’ 

. 4 6.033 

4 103 

4 5 

4 33,000 

>155 

>117,700 



4 103 


5 1.6-3.1 

5 3C0-450 : 
22 4.58 
».i*300-400 , 

5 500-1,000 

•200,000-250, OoO 
22 4,000 
*. i* 48,000-63,000 




Intoxicant, asphyxiant; act on 
blood. 

Asphyxiant. 

Asphyxiant; acts on blood. 

Asphyxiant. 

Respiratory irritant. . 

Asphyxiant.. 

do 











2 54 

2 30,000 










Carbon bisulphide. 

Carbon dioxide. 

Carbon monoxide. 

Carbon tetrachloride. 
Chlorine. 

Chloroform. 

.«'4.’5‘ 

1 0.010 
•3.3 

.8*7i8* 

‘ 3.5 
«674 



.***6.044* 

”*i*i5.*i* 

*i*6.’088*. 

’"‘i’so.T 

« 0.57 

2 10 

2 0.0029 

2 1 

«500 

2 1,600 

2 1 
*200 

6 0. 57 

2 25-40 

2 0. 012 

2 25-30 

6 500 

2 4,000-6,300 

2 5,100-6,200 

.V, 6 2.29 

2 150-200 

2 0.12-4). 17 
*70 

.W V 2,066’ 

2 24.000-32,000 

2 40-60 

2 14,000 

. 4 ‘6.’6i5* 

. 4 5 

* 9 *,*1*3^5" 

“>Vi26* 

'»Vi*2*600^4,’400* 

.>1 25,900 

*1*3 * 

12.5 

* * *» *1*2,"600* 
.1 860* 

. 

>ii»i* 466 
>ii; iV 120* 

1 >11 :i* 63,666 

j >11 » 25*000 

1 >u» i* 44,000 

SV1V366I466* 

2,13 2.9 

2 300-400 

*, “48*666163,666* 
2.18 1,000 

2 62,000-82,000 

y.. 

* 2.2’ 

1* 1.7 









*5-10 

2 1,400-2,800 

2 15-25 

*4,300-7,100 



1 4 60 

1 4 17,000 











Anaesthetic. 

Dichlorethylene. 









2 0.015 

1 10 

2 0.075-0.150 

*50-100 

*2.2-3 

2 1,500-2,000 

1 0.1-0.3 

166-200 







4,5 15 

4.» 1,000 
<1,000 
• 1,200 




Gasoline.21 









2 0.022-0.044 

2 20-40 

2 0.055-0.066 

*50-60 

2 0.132-0.186 

2 120-1.50 

4 » 1 5 27-1 

M5 250-1,000 

i0.2 

1180 

1 0.1 

1 90 



4 1.1 

*3.3 

*3000 

*1.000-2,000 


f I’aralyzes nervous centers im- \ 

Hydrogen chloride. 









2 0.14-0.21 

2 100-150 

2 0.28-0.42 

2 200-300 

*0.70-0.97 

2 500-700 





*1.4-2.8 


\ pairs tissue oxidation. / 

Reduces haemoglobin of the 11 od... 

Hydrogen cyanide. 

Hydrogen sulphide. 









2 0.005-0.01 

*0.5-1 

*0.03 

*3 



16 0.95 














i« 0.076 

’ 16 62 

16 .124 

16 101 

i« 0.048 

2 0.001-0.002 

i« 39 

2 0.2-0.4 

.** 6.* 66563’ 

.Vi" 

16.14-.19 

117-154 

16 1.46 

i« 775 





i«.50 

i«410 



i«0.95 

M775 


.do. 

Asphyxiant; respiratory irritant. 

Respiratory irritant. . 

Asphyxiant: anaesthetic. 

Iodine. 

Nitric oxide. 28 





i« o.iii 

16 62 

16.19 

1« 101 


16 39 


16 6: 22-6.29 

. i«‘ii7-i54 


.iV 775 

i° 6.90 

.10*566' 



> u 80 

.1*6*4*10 

>U9,600 

>31,000 

150 



.iVi.*46* 

.“775* 

“6.2 

Nitrobenzene. 

N i trogen peroxide. 

Pen tachlorethanc. 

. i 0.023* 

*i 5.6 

* ’ Vo. oi6 

. V «’ 

.*i*0.*6i26* 

i 3.1* 

Vo.oiq" 

“*‘*1*4*8* 

.’»’6:664' 

’ ’ ’ ’ * 

‘ 2 ‘6.‘63^6.‘679' 

.*'i 66^266" 

* * * 6. i4S-0.*237 

."« 40(Wi66' 

Vo.’ 62’ 

.* 4 *5* 

1*6.4 

.*1*99* 

MO 6.35' 

. 

10.20 

.loiio 

."‘*25 




.do. 

Lachrymator—respiratory in int... 
Acts on blood and nervouss em... 

Respiratory irritant. 

.do. 

Respiratory irritant—lachrym.itor... 

Asphyxiant. 

Respiratory irritant. 

Asphyxiant, anaesthetic.. 

Perchloretliylene 

Phosgene. 

Phosphine. 


















.Vi20" 


















.’ 2 ’6.*6o4’ 

.***6.7* 

’ 2 ’6.*6 m >.’62 

*2-4 

2 0.3-0. 5 

.59-90' 










.*3.5 * 

.*8620 


Phosphorous pentachloride. 
Phosphorous trichloride. 

. Sulphur dioxide. 

. Tetrachlorethane. 

, Toludine. 

Trichlorethy lene. 

“>‘« 0.008-0.013 

3-5 

18 0.052 

18 20 

18 0.021-0.031 

18 8-12 

18 0.052 

18 20 

*0.052-0.070 

*20-30 

2 0.13-0.52 

2 50-200 

2 1-1.3 

•400-500 

18 o.2e 

18 100 


















"*‘6.025^6 ‘ i ’ 

. 2 6-23 

."*’6.* 4-6.6* 

.V9i-i46’ 









>n» 1* 50 

>>1.1*266 

>“.‘•7,300 
>i>.“ 37,66 o' 


J:::::::::::::::::::; 


=E 

1* 9.1 


i Chemical Warfare Service, American University Experiment Station, Washington, D. C. 

• Lehmann K B . Tabclie der kleinsten Mengen schadlicher Fabrikgase, welche noch pitig dnd und 

der Mengen,welc’heallenfalls ertragen werden: inbookbvKobert,Rudolf,KompenJum derpraktischen 
Tntikoloeie aum Gebrauche fur Ante, Studierende und Medmnalbeamte, Stuttgart, 1912. p. 45_ 

■ ,nSSn tetrachloride for hair shampooing; Jour. Am. lied. Assoc., Aug. 28,1909, vol. 

**5 icohn-Abrest, E., Toxicological Report onGasra: Annate des Falsiiications, vol. 8,1915, pp. 215-239. 

• Thompson, W. G., Occupational diseases, New York, 1914, -2» P. jkvjao 

on S]Stu of Mines, Tech. Paper 82, 1917, 103 pp. 


Ind. Eng. Chem., vol. 11, April, 1919, pp. 335-33S. . 

» Burrell, G. A., Sibert, F.M., anu Robinson, I. W., Relative effects of carbon monoxide on small ani¬ 
mals; Bureau of Mines Tech. Paper 62,1914, pp. 23. Mice, death in 125 minutes, 8.9 Mg./L.-7,700 p. p. m.; 
dogs, collapsed in 23 minutes (recovered), 2.8? Mg./L.-2,500 p. p. m. Men walking collapsed in 60 minutes 
(blood one-lialf saturated), 2.29 Mg./L.-2,000 p.p.m. ... . . . . .. , , 

■“Haldane, J. S., quoted by Hamilton, Alice, Industrial poisons used or produced m the manufacture 
of explosives; Bureau of Labor, Bull. 219, May, 1917, p. 16. 

it Lehmann, K. B., Experimentelle studien liber den Einfluss teehnisch und hygienisch wichtiger 
Gase und Dampfe auf den Organismus (XVI-XXIII). Die Gechlorten Kohlenwasserstoff der Fettreihe 
nebst Betraehtungen liber die einphasische und zweiphasische Giftigkeit atherischer K6rper; Archive 
ffir Hygiene, vol. 74,1911, pp. 1-60. 


“ Herrmann, Georg., Wirkung GechJorter Kohlenwasserstoffe, Chloroform, Tetrachlorkohlenstoff, 
Trichlorathylene, Dichlorathylenc; Inaugural dissertation, Wurzburg, Carl Fuchs, 1911,50 pp. 

Is Slovtzov. B. I., The influence of the chlorine content of the air upon the animal organism. Arch. 
Sci. Vet^rinaires, 1916, 3; Chem. Ab., vol. 12, Apr. 20,1918, p. 831. 

14 Fieldner, A. C., Katz, S. H., and Kinney, S. P., Test oxygen breathing apparatus, Bureau of Mines 
experiments with rubber bags to determine their permeability when in contact with gasoline vapor. 
Tests made following death of a man in a gasoline tank; Oil and Gas Jour., vol. 18, Feb. 27,1920, pp. 78-79. 

15 Grubbs, S. B.: Detection of hydrocyanic acid gas. Use of small animals for this purpose: Pub. 
Health Reports: vol. 32,1917, pp. 565-570: Chem. Abs., vol. 12 1918, pp. 1744-1745. 

16 Lehmann, K. B., and Dr. Hasegawa, Studien fiber die Wirkung teehnisch und hygienisch wichtiger 
Gase und Dampfe auf den Menschen (XXXI). Dienitrosen Gase; Stickoxvdul,Stickstoffdioxide,salpo- 
trige Safire, Salpetersaure: Archiv fttr Hygiene, vol. 77,1913, pp. 323-368. These experiments were per¬ 


formed with nitric oxide. Analysis of concentrations were made in terms of nitrons and total nitric 
acid content. The total nitric acid content has been calculated to Mg./L. and p. p. m. of nitric oxide 
and nitrogen peroxide. It was found that nitrous acid and nitric acid mixed equimoleeularly act 
together as if all the nitrogen oxidation products were present in the mixture in the form of nitric 
acid. Short exposure to 0.29-0.48 Mg./L. (240-390 p. p. m.) of nitric oxide or 0.44-0.73 Mg./L. (240-39.1 
p. p. m.) nitrogen peroxide was found to be very dangerous to man, no time given. 

17 Holmes, J. A., Franklin, E. C., and Gould, R. A.; Report of Selby Smelter Commission, Bureau cf 
Mines Bull. 98,1915, p. 36. 

18 Fieldner, A. C., and Katz, S. H., Army gas masks insulphur dioxide; Eng. and Mining Jour., Apr. 19. 
1919, vol. 107, pp. 693-695. 

“ Average. 


" Pullen, R. W., Acute phosgene prisoning and its therapy; thesis, University of Wisconsin, 1 
” rorlow, " •> Case of gasoline poisoning; Med. and Surg. Jour., vol. 6, 1914, pp. 621-624. 

” Henderson, Y., Carbon monoxide noisopinv; Jour. Am. Med. Assoc., vol. 67, Aug. 19,1916, r 
Rough estimate of lethal dose for man: 0.2 per cent, 4 to 5 hours; 0.4 per cent, 1 hour; 2-5 per o 
few minutes. 

“, H ? ldane ’ J- S., Taken from article by Irvine, L. G., Gassing accidents from fumes of explosives: Brit. 
Med. Jour., vol. 2,1916, pp. 162-163. 


55299°—21. (To face page 56.) 
































































































































































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PUBLICATIONS ON BREATHING APPARATUS AND GASES FROM 

FIRES. 

A limited supply of the following publications of the Bureau of 
Mines has been printed and is. available for free distribution until the 
edition is exhausted. Requests for all publications can not be granted 
and to insure equitable distribution applicants are requested to l imi t 
their selection to publications that may be of especial interest to them. 
Requests for publications should be addressed to the Director, Bureau 
of Mines. * 

The Bureau of Mines issues a list showing all its publications avail¬ 
able for free distribution as well as those obtainable only from the 
Superintendent of Documents, Government Printing Office, on pay¬ 
ment of the price of printing. Interested persons should apply to the 
Director, Bureau of Mines, for a copy of the latest list. 

PUBLICATIONS AVAILABLE FOR FREE DISTRIBUTION. 

Bulletin 42. The sampling and examination of mine gases and natural gas, by 
G. A. Burrell and F. M. Seibert. 1913. 116 pp., 2 pis., 23 figs. 

Bulletin 105. Black damp in mines, by G. A. Burrell, I. W. Robertson, and G. G. 
Oberfell. 1916. 92 pp. 

Technical Paper 11. The use of mice and birds for detecting carbon monoxide 
after mine fires and explosions, by G. A. Burrell. 1912. 15 pp. 

Technical Paper 13. Gas analysis as an aid in fighting mine fires, by G. A. Burrell 
and F. M. Seibert. 1912. 16 pp., 1 fig. 

Technical Paper 59. Fires in Lake Superior iron mines, by Edwin Higgins. 
1913. 34 pp.,2 pis. 

Technical Paper 62. Relative effects of carbon monoxide on small animals, by 

G. A. Burrell, F. M. Seibert, and I. W. Robertson. 1914. 23 pp. 

Technical Paper 82. Oxygen mine rescue apparatus and physiological effects 
on users, by Yandell Henderson and J. W. Paul. 1917. 102 pp., 5 pis., 6 figs. 

Technical Paper 103. Organizing and conducting safety work in mines, by 

H. M. Wilson and J. R. Fleming. 1917. 54 pp., 35 figs. 

Technical Paper 122. Effects of oxygen deficiency on small animals and on men, 
byG. A. Burrell and G. G. Oberfell. 1915. 12 pp. 

Technical Paper 134. Explosibility of gases from mine fires, by G. A. Burrell and 
G. G. Oberfell. 1916. 31 pp., 1 fig. 

Technical Paper 150. Limits of complete inflammability of mixtures of mine 
gases and of industrial gases with air, by G. A. Burrell and A. W. Gauger. 1917. 13 
PP-, 2 figs. 

Technical Paper 185. Use of the interferometer in gas analysis, by F. M. Seibert 
and W. C. Harpster. 1918. 18 pp., 1 pi., 5 figs. 

Technical Paper 238. Carbon dioxide and oyxgen detectors, by A. C. Fieldner 
and others. 1920. 23 pp., 3 pis., 12 figs. 

Miners’ Circular 4. The use and care of mine-rescue breathing apparatus, by 
J. W. Paul. 1911. 24 pp., 5 figs. 


57 


58 GAS MASKS FOR GASES MET IN FIGHTING FIRES. 

Miners’ Circular 10. Mine fires and how to fight them, by J. W. Paul. 1912. 
14 pp. 

Miners’ Circular 14. Gases found in coal mines, by G. A. Burrell and F. M. 
Seibert. 1913. 23 pp. 

Rescue and recovery operations in mines after fires and explosions, 
by J. W. Paul and H. M. Wolflin. 1916. 109 pp. 

PUBLICATIONS THAT MAY BE OBTAINED ONLY THROUGH THE SUPER¬ 
INTENDENT OF DOCUMENTS. 

Bulletin 44. First national mine-safety demonstration, Pittsburgh, Pa., October 
30 and 31, by H. M. Wilson and A. H. Fay, with a chapter on the explosion at the 
Experimental Mine, by G. S. Rice. 1912. 75 pp., 7 pis., 4 figs. 15 cents. 

Bulletin 62. National mine-rescue and first-aid conference, Pittsburgh, Pa., 
September 23-26, 1912, by H. M. Wilson. 1913. 74 pp. 10 cents. 

Technical Paper 14. Apparatus for gas-analysis laboratories at coal mines, by 
G. A. Burrell and F.M. Seibert. 1913. 24 pp., 7 figs. 5 cents. 

^Technical Paper 24. Mine fires, a preliminary study, by G. S. Rice. 1912. 51 

pp., 1 fig. 5 cents. 

Technical Paper 77. Report of the committee on resuscitation from mine gases, 
by W. B. Cannon, G. W. Crile, Joseph Erlanger, Yandell Henderson, and S. J. Meltzer. 
1914. 36 pp., 4 figs. 5 cents. 


INDEX. 


A. Page. 

Absorbents, See Charcoal; Copper sulphate; 

Silica gel; Soda lime. 

Acetone, properties of. 56 

Acid fumes, absorbents for. 2$ 

effect o f breathing. IS 

use of gas masks for. IS 

Air masks, description of. 21 

view of...:. 24 

Alcoho 1 vapor, t oxieit y o f.. 56 

Allison, V. C., work cited. 56 

Ammonia, dangerous percentages of... 14 

canisters for. 11 

effects of breathing. 13 

effect on human skin. 14 

properties of.. 13,56 

Ammonia poisoning, treatment for. 14 

Anilin,'properties of. 56 

Arsenic trioxide, properties of. 56 

toxicity of. 56 

B. 

Benzene, propert ies o f. 56 

Bray, W. C., work cited. 29 

Bromine, propert ies of.. 56 

Bum'll, G. A., work cited. 9,56 

C. 

Camden, N. J., fir© in, use of masks at. 6 

Carbon bisulphide, properties of. 56 

toxicity of. 56 

Carbon dioxide, toxicity of. 56- 

Carbon monoxide, danger from. 30 

dangerous quantities of. 9 

detection of..-. 10 

effects o f breathing. 9 

effect on Army masks. 5 • 

from illuminating gas, danger of. 15 

production of.. * .7, S, 9 

toxicity of. 8,56 

See also Mine tin's. 

Carbon monoxide poisoning, symptoms and 

effects of.. 10 

Carbon monoxide tests for gas masks, appara¬ 
tus for, description of . 30 

view of. 30 

chamber for, view of.. 31 

discussion of.. 35 

results of. 36 

Carbon tetrachloride, dangers from . 19,42 

decomposition of, tests of, n'sults of.. 41 

effects o f breathing . 20 

in fix© ext inguishers, danger from . 42 

properties and toxicity of.. 18, 56 

use of gas masks for . 20 

See also Fire extinguisher liquids. 

Carter, l\ B., letter cited . 6 

Celluloid, fumes from, effect on masks . 4 


Page. 


Chaney, N. K., work cited. 27 

Charcoal, activated, use as filter of.. 11,17, IS, 27,2S 

Chemical Warfare Service, work cited.19,56 

Chicago, Ill., fin' in, failure of masks at. 4 

Chlorine, commercial uses of.. 15 

effects of breathing. 15 

properties and toxicity of.. 15,56 

use of gas masks for.*. 15 

Chloroform, properties and toxicity of. 56 

Combustion, chemistry of. 6-S 

Copper sulphate, as absorbent, use of. 28 

Cotton pads, as filter, use of.... 11 

Cotton-smoke, man test, for canisters.-. 49 

D. 

Detroit, Mich., fin' in, failun' of masks at_ 4 

Piehlorethylene, properties and toxicity of.. 56 

riuluth, Minn., fire in, use of masks at. 6 

F. 

Fieldner, A. C., work cited. 16,28,56 

Fire-extinguisher liquids, content of. 39 

distillation tests of, results of. 39 

See Carbon tetrachloride. 

Fire-fighters’ gas masks, specifications for... 46 

Fire fighting, with gas masks, discussion of.. 4,5,6 

Forlow, J. W., work cited... 56 

Foster, C. L. N., work cited. 10 

Francis, H. J., work cited. 5 

Franklin, E. C., work cited. 56 

Frazer, J. C. W., work cited. 29 

G. 

Gases, conversion table for. 52 

met in fighting fires.. 11 

poisonous amounts of.. 56 

Gas masks, adjustment of. 26 

view of. 26 

Army type, canister for, figure showing.. 33 

tests of.48-49 

view of. 25 

limitations of. 45 

R. F. K. mask; Tissot gas mask. 

atmospheres not affected by. 30 

care of.. 24 

for different gases, colors required for.... 46 

invest igat ions of, purpose of. 4 

tests of. 26 

apparatus for, figure showing. 24 

also Carbon monoxide tests; 

Smoke tests. 


See also Acid fumes; Air masks; Ammonia, 
canisters for; Chlorine: Fire-fight¬ 
ing; Gasoline vapors; Hydrochloric 
acid gas; Organic vapors; Oxygen 
breathing apparatus; Respirators; 
Smoke; Soot; Sulphur dioxide; 
Tar. 


59 
























































































60 


INDEX 


Page. 


Gasoline vapors, dangerous amounts. 56 

effects o f breathing. 16 

explosive range of. 16 

properties. 56 

use of gas masks for. 17 

Gibbs apparatus, view of..... 20 

Gould, R. A., work cited.,. 56 

Grubbs, S. B., work cited. 56 

H. 

Haldane, J. S., work cited. 10,56 

Hamilton, M. A., work cited. 12 

Hasegawa, Dr., work cited. 56 

Hawk, J. Q., letter cited. 6 

Henderson, Yandell, acknowledgment to.... 4 

work cited. 9,10,20,56 

Hermann, Georg, work cited. 56 

Holbrook, E. A., acknowledgment to. 4 

Holmes, J. A., work cited. 56 

Hood, O. P., acknowledgment to. 4 

Hydrochloric acid gas, effects of breathing.. 19 

use of gas masks in. 19 

Hydrogen chloride, properties and toxicity of. 56 
Hydrogen cyanide, properties and toxicity of. 56 
Hydrogen sulphide, properties and toxicity of 56 

I. 

Illuminating gas, effect on Army masks. 5 

See also Carbon monoxide. 

Iodine, properties of. 56 

Irvine, L. G., work cited. 12 

J. 

James, J. D., on tests of Tissot gas masks. 21 

K. 

Katz, S. H., work cited. 16,56 

Kenlon, John, work cited. 3 

Kinney, S. P., work cited. 16, 56 

Kohn-Abrest, E., work cited. 56 

L. 

Lamb, A. E., work cited.27,29 

Lehmann, K. B., work cited. 14,15,17,20,56 

M. 

Methane, danger from. 30 

Mine fires, breathing apparatus for use in.... 43 

gases from, analyses of. 44 

Moline, Ill., fire in, use of masks at. 6 

N. 

New Brunswick, N. J., fire in, use of masks at. 5 

New York City, fire in, failure of masks at.... 4 

Nitric oxide, properties and toxicity of. 56 

Nitrobenzene, properties of. 56 

Nitrogen, oxides of, effect on Army masks.... 5 

Nitrogen peroxide, effects of breathing. 12 

occurrence of. 11 

properties and toxicity of. 12,56 

O. 

Oliver, Thomas, on effects of breathing nitro¬ 
gen peroxide. 12 

Organic vapors, absorbents for. 27 

use of gas masks for. 18 


Page. 


Oxygen, amount required by man. 7 

Oxygen breathing apparatus, description 

and use of. 21 

See also Gibbs apparatus; Salvus breath¬ 
ing apparatus. 


P. 


Parker, D. J., acknowledgment to. 4 

Patrick, W. A., patent cited. 29 

Paul, J. W., acknowledgment to. 4 

work cited..,.20,56 

Pentachlorethane, properties and toxicity of. 56 

Perchlorethylene, properties and toxicity of. 56 

Perrott, G. St. J., work cited. 28 

Phosgene, properties and toxicity of. 56 

Phosphine, properties of. 56 

Phosphorous pentachloride, properties of.... 56 

Phosphorous trichloride, properties and tox¬ 
icity of. 56 

‘'Pig snout’’ respirator, views of. 22 

Pittsburgh, Pa., fire in, use of gas masks at. 5 
Pullen, R. W., work cited. 56 


R. 

Rags, fumes from, effect on masks. 

Respirator, description of. 

See also “Pig snout” respirator. 

R. F. K. mask, description of. 

figure showing. 

view of. 

Rice, G. S., acknowledgment to. 

Robinson, I. W., work cited.. 

Rochester, N. Y., fire in, failure of masks at 


Salvus breathing apparatus. 21 

Seibert, F. M., work cited. 9,56 

Silica gel, as absorbent, use of.. 29 

Slovtzov, B. I., work cited. 53 

Smoke, use of gas masks in. 5,11 

See also Combustion, chemistry of; Fire¬ 
fighters’ masks; Gas masks. 

Smoke tests for gas masks, apparatus for, 

description of. 31 

chamber for, figure showing. 32 

discussion of_ * . 38 

results of.-•. 37 

See aZso'Cotton-smoke. 

Soda-lime, as absorbent, use of.27,28 

ingredients of. 28 

Soot, use o f gas masks for. 11 

Spring Lake, N. J., fire in, use of masks at_ 5 

Sulphur, fumes from, effect on masks. 4 

Sulphur dioxide, dangerous amounts of. 56 

detectable percentages of. 13,56 

effects of breathing. 12 

occurrence of. 13 

properties of. 12,56 

use of gas masks for. 13 


4,5 

21 

22 

23 

24 

4 
56 

5 


T. 


Tar, in smoke, use of gas masks for. 11 

Tetrachlorethane, properties and toxicity of. 56 

Thompson, M. D., on suffocation by nitrogen 

peroxide. 12 



















































































INDEX. 


Page. 

Thompson, W. G., work cited.1»,56 

Tin tetrachloride, Tnan test for canisters. 4& 

Tlaaot ?as mask, description of..21.22 

tests of. 21 

use of.. 17 

views of.23.24 

To bacco-~inoke test, for canisters. 43 

Totidine, properties of. 56 

Trif-hlorethane, properties and toxicity of... 56 


y. 

Yefey, G. A., work cited 

W. 

Waller, A. D., work cited. 
Waters, C. H., work cited 
wagon, C. Wi, letter cited. 
Wilson, R. E., work cited 

Y. 

Yaclick. Max, work cited. 


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LIBRARY OF CONGRESS 



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